Jessie was later wondering if convincing the Doctor to let Donna fly the TARDIS was a good idea as she clung high to where she was perched up in the coral structures. "I can't believe I'm doing this!" Donna exclaimed as she tried a few levers.

"No, neither can I," the Doctor admitted with a grimace before jumping. "Oh, careful!"

"Easy there, girl," Jessie soothed, stroking the coral structure she was on. "It's all right."

The TARDIS settled down a little bit. "Thank you, my Wolf."

She caught the Doctor's brilliant smile as he guided Donna through piloting. "Left hand down, left hand down!" Donna quickly did, and he readjusted her. "Getting a bit too close to the 1980s."

"What am I going to do, put a dent in them?" Donna snorted.

"Well, someone did," the Doctor commented.

There was a phone trill, and Jessie reached for her pocket, looking for her Galaxy, before frowning. "That's not mine," she called down before shuffling through her other pockets before she recognized the ringtone, and she began to grin like a Cheshire cat, and she quickly jumped down and headed for the console, scrambling around. "Where is it . . . ?"

"You've got a mobile?" Donna asked the Doctor. "Since when?"

"It's not ours," the Doctor told her.

Jessie finally found the phone and answered it with a grin. "Hello?"

"Bad Wolf!" Martha's voice cheered. "It's Martha, and I'm bringing you back to Earth!"

"Where are we headed?" Jessie asked, heading over to the console.

"April 26, 2017."

"On our way."

"Oh, by the way? I think you'll like a surprise I've got for you."

"Oh, yeah, now I'm really excited," Jessie drawled as she piloted the TARDIS one handed, much to the gawking of her husband and the blinking of Donna.

"No, you really will."

"OK."

Martha laughed. "Oh, I've missed you!"

"Missed you, too," Jessie grinned, hanging up and pulling the last lever, making the TARDIS engines go. She put the phone in her pocket before smirking at the Doctor. "And that is how you make the TARDIS behave," she told him smugly, patting the rotor, hearing the satisfied hum around her.

"You," the Doctor told her, poking her in the forehead before kissing the top of her head. "Are incredible."

"I know," she replied with a grin before running over to the TARDIS doors when it landed, and she stepped out, looking to her right before turning to her left.

And her eyes widened, her face splitting in a grin. "Steve!" she shouted, running that way.

Captain Steve Rogers turned at her voice, and he turned to the black woman next to him, who nodded with a smile on her face before he turned and hugged her tightly. "So they were telling the truth!" he laughed.

"Yes, they were," Jessie laughed, wrapping her arms around his neck and letting him spin her around with a squeal. She dropped down and engulfed Martha next, the woman giving her just as tight of a hug. "The Woman Who Walked The Earth! How've you been?"

"Been doing all right," Martha replied with a grin. "Never mind me, how about you?"

"Martha Jones," the Doctor greeted as he stepped out.

Martha smirked at him. "Doctor," she countered, before he grinned and ran to hug her as well.

"You haven't changed a bit!" he declared.

"Neither have you two," Martha laughed.

"And Captain Rogers," the Doctor added, holding out a hand. "I hope you don't try and kill me."

"I had a mind to a few months ago," Steve warned with a grin, but he shook his hand. "Then I heard of a Time Lord wedding that I missed."

"Yeah, sorry about that," Jessie apologized. "Sort of short notice."

"How's the family?" the Doctor asked Martha.

"You know, not so bad," Martha replied with a shrug. "Recovering."

Jessie looked over her shoulder as Donna stepped timidly out of the TARDIS. "What about you?" the Doctor asked.

Martha saw Donna, and she gave a grim smile. "Right," she said. "Should have known. Didn't take you long to replace me, then."

"Oi!" Jessie squeaked, playfully swatting the back of Martha's head. "Shame on you for thinking we would replace you! For your information, we had nearly eight months before we brought Donna with us!"

"She did that to us all the time," Steve told Martha sympathetically, rubbing the back of his own neck.

"Now, don't start fighting," the Doctor warned, bringing Donna over. "Martha, Steve, Donna. Donna, Steve, Martha. Please don't fight. Can't bear fighting."

"You wish," Donna snorted, shaking both of their hands. "I've heard all about you two," she told them. "These two talk about you all the time."

"I dread to think," Martha commented, looking at the Doctor as Jessie shuffled on her feet.

"No, no, no," Donna insisted. "No, they say nice things. Good things. Nice things. Really good things."

"They've told you everything, haven't they?" Steve asked.

"Oh, my God, they really have!" Martha groaned.

Jessie caught a glimmer on her hand and gasped. "Oh, my God!" she squealed, jumping over to her and grabbing her left hand and looking at the ring on her finger. "You should have mentioned you were engaged! Who's the lucky man?"

Martha blushed. "I didn't say because I knew you would act like this," she whispered.

"Who to?" the Doctor repeated.

"Tom," Martha replied with a smile. "That Tom Milligan. He's in pediatrics. Working out in Africa right now." She rolled her eyes. "And yes, I know, I'e got a doctor who disappears off to distant places. Tell me about it."

"Not much has changed about you, though," Steve told Jessie with a smile. "When I got the whole spiel, I didn't know what to expect."

"Is he skinny?" Donna asked Martha curiously.

"No," Martha replied. "He's sort of . . . " She took a quick look at Steve and blushed. "Strong," she admitted, and Steve blushed as well.

"He is too skinny for words," Donna told them, jerking her thumb at the Doctor, who looked offended at the statement. "You give him a hug, you get a paper cut! I don't know why she's not bleeding all over the floor right now."

"Oi!" Jessie complained, giving her a swat as well.

"Oh, I'd rather you were fighting," the Doctor sighed.

Jessie blinked. "Hold on a minute, why are you - " She pointed at Steve. "Here in London?"

"Speaking of fighting . . . " Martha began.

"Doctor Jones, Captain Rogers, report to base, please. Over."

Martha took a walkie-talkie from her belt and answered it. "This is Doctor Jones with Captain Rogers," she spoke into it. "Operation Blue Sky is go, go, go. I repeat, this is a go." She readjusted her grip and waved them on. "Let's go."

Jessie and the Doctor looked at each other as they followed Martha and Steve through the alley. "She's in all black," she told the Doctor. "And Steve's in his uniform."

"I noticed," he replied.

They stopped short when they came around the corner to see a rather large group of jeeps, trucks, and men in black with machine guns run past. "Unified Intelligence Taskforce!" someone shouted as men in black with red caps ran out, and Jessie recognized the uniform vaguely from Downing Street. "Raise that barrier, now!"

"Factory's called ATMOS," Jessie added, looking at the building they were raiding.

"Leave those safeties on, lads! They're non-hostiles!"

"All workers, lay down your tools and surrender."

They watched with a critical eye, and a little worry, as UNIT forced ATMOS workers to their knees. "Greyhound Six to Trap One," Steve shouted as he walked forward, calling into his own walkie-talkie. "B Section, go go go! Search the ground floor! Grid pattern delta!"

"What are you searching for?" the Doctor wondered.

"Illegal aliens," Martha replied.

"This is a UNIT operation. All workers lay down your tools and surrender immediately."

"B Section mobilized," Steve announced.

"E Section, F Section, on our command!" Martha ordered as she and Steve ran to see to the operation.

Jessie and the Doctor watched Martha go in shock. "Is that what you did to her?" Donna asked. "Turned her into a soldier?"

The two Time Lords turned and looked at each other in worry. Had they really done that?

***

Jessie beamed at Martha's badge as she and Steve rejoined them. "You're qualified now," she observed. "You're a proper doctor."

"UNIT rushed it through, given my experience in the field," Martha replied, leading them towards the back of a truck. "Here we go. We're establishing a field base on sight. They're dying to meet you."

"Wish I could say the same," the Doctor muttered as Steve held the door open for them.

Jessie took one look around and whistled. "Oh, that is beautiful," she said, bending to investigate every little inch of the pristine base. "I never would have known this was a mobile base!"

"Operation Blue Sky complete, sir," Martha announced as she walked up to the man in military fatigues. "Thanks for letting me take the lead with the Captain. And this is the Doctor. Doctor, Colonel Mace."

"Sir," Mace told him, throwing up a salute.

"Oh, don't salute!" the Doctor groaned.

"But it's an honor, sir. I've read all the files on you. Technically speaking, you're still on staff. You never resigned."

"Oh, is that so?" Jessie asked, folding her arms and quirking an eyebrow at her husband. "And all those times you nagged me about what I did?"

"In my defense, that was back in the 70s," he told her before making a face. "Or was it the 80s?" He shook his head. "But it was all a bit more homespun back then."

"Times have changed, sir," Mace told him.

"Yeah, that's enough of the sir," the Doctor added, tugging Jessie closer to him and throwing quick looks around the room at the men who had turned to stare. "Only this girl gets to call me that."

She smiled at him. "I'm the Bad Wolf," she told him.

"I told you about Agent Vertigo, right, Colonel?" Steve asked.

Mace's eyes widened, and he threw up another salute. "Agent Nightshade, I never thought I would see the day when I had two Avengers in UNIT."

"Oh, I'm not UNIT," Jessie sighed, but she threw up a firm salute as well. "But I'll take that."

"Come on, though, Doctor," Martha told him with a smile. "You've seen it! You've been onboard the Valiant." Jessie cringed at that, and the Doctor pulled her tighter. "We've got massive funding from the United Nations, all in the name of Home World Security."

"A modern UNIT for the modern world," Mace added.

"What, and that means arresting ordinary factory workers in the streets in broad daylight?" Donna snorted. "It's more like Guantanamo Bay out there."

"Well, not entirely Gitmo," Jessie mused thoughtfully. "But good analogy."

"Donna, by the way," Donna continued with a nod at Jessie. "Donna Noble, since you didn't ask. I'll have a salute."

Steve smirked a little at that as Mace looked around for obvious help. The Doctor nodded, and Mace saluted her. "Ma'am," he greeted.

"Thank you," Donna muttered.

"So does anyone want to tell us what exactly is going on inside that factory?" Jessie asked, getting back to the point.

"Yesterday, fifty two people died in identical circumstances, right across the world, in eleven different time zones," Mace began, turning their attention to the huge screen on the wall. "Five a.m. in the UK, six a.m. in France, eight a.m. in Moscow, one p.m. in China."

"You mean they died simultaneously," the Doctor summed up.

"Exactly," Mace said. "Fifty two deaths at the exact same moment worldwide. Captain Rogers was on call in Germany for one, and knowing his experience with SHIELD, we asked him to come in."

"How did they die?"

"They were all inside their cars."

"They were poisoned," Martha elaborated. "I checked the biopsies. No toxins. Whatever it is left the system immediately."

"What have the cars got in common?" the Doctor asked.

"Completely different makes. They're all fitted with ATMOS, and that is the ATMOS factory."

"What the hell is ATMOS?" Jessie asked.

"Oh, come on," Donna snorted. "Even I know that! Everyone's got ATMOS!"

"Which is why SHIELD stopped using ATMOS style cars once I contacted them about it," Steve added as they were led off. "They're on call in case we need them."

Jessie grinned at him. "Oh, I missed you."

"I missed you, too."

***

"Stands for Atmospheric Omission System," Martha explained. "Fit ATMOS in your car, it reduces CO2 emissions to zero."

"Zero?" the Doctor asked in surprise. "No carbon? None at all?"

"And you get sat-nav and twenty quid in shopping vouchers if you introduce a friend," Donna added. "Bargain."

"And this is where they make it, Doctor," Mace told him, gesturing around the factory. "Shipping worldwide. Seventeen factories across the globe, but this is the central depot, sending ATMOS to every country on Earth."

"And you think ATMOS is alien," Jessie guessed.

"It's our job to investigate that possibility." He held out an arm. "Doctor? Bad Wolf?" The Doctor eyed the workers as they slipped through a plastic curtain, and they instantly began inspecting the device on the table. "And here it is, laid bare. ATMOS can be threaded through any and every make of car."

"You must've checked it before it went on sale," the Doctor told them.

"We did," Martha replied. "SHIELD did, too. We found nothing. That's why I thought we needed an expert, and Steve agreed on who we needed to call."

"Really? Who'd you get?" the Doctor asked curiously. He cringed when Jessie's palm made contact with his head, and she folded her arms, raising an eyebrow pointedly before he pointed between the two of them. "Oh, right! Us! Yes. Good."

Martha smiled, shaking her head as she and Mace left. "OK," Donna said. "So why would aliens be so keen on cleaning up our atmosphere?"

"A very good question," the Doctor praised.

"Most of them aren't that friendly," Steve told them. "HYDRA certainly wouldn't."

"Oh, HYDRA," Jessie scowled. "Have you found Bucky yet?"

"No," Steve sighed, shaking his head. "Sam and I are still looking."

"Maybe they want to help," Donna offered. "Get rid of pollution and stuff?"

"Not with how many cars are on this planet," Jessie replied, shaking her head.

"There are eight hundred million," the Doctor told Donna, whose eyes widened. "Imagine that. If you could control them, you'd have eight hundred million weapons."

"HYDRA would love that, though," Jessie commented.

***

Some time later, the Doctor tossed something over his shoulder to Jessie, who caught it and peered through it. "You're kidding me," she gasped as Martha and Mace reentered. "You're actually telling me - ?"

"Ionizing nano-membrane carbon dioxide converter," the Doctor confirmed. "Which means that ATMOS works. Filters the CO2 at a molecular level."

"We know all that, but what's its origin?" Mace asked, stepping closer. "Is it alien?"

"No," the Doctor replied. "Decades ahead of its time." He eyed Mace warily and opened his mouth to say something -

When Jessie stepped in first. "'Scuze me, Colonel, but could you stand back a bit?"

"Sorry," Mace replied, looking at her in confusion. "Have I done something wrong?"

"You're carrying a gun," she replied, eyeing it. "I don't like people with guns around my husband, all right?"

"But you carry a gun."

"So I've noticed." She raised an eyebrow. "But the one I have is an ICER. It only knocks people out. It doesn't kill. And so far, within the last 72 hours, both of us have nearly died, once because of a gun being held on us." She made a motion. "So go on."

He furrowed his eyebrows. "If you insist," he replied, turning on his heel and leaving.

"Tetchy," Martha told her.

"Well, it's true," Jessie told her, shaking her head and moving back around to the Doctor.

"He's a good man," Martha spoke up.

"People with guns are usually the enemy in my books," the Doctor finally brought up. "Especially lethal ones." He looked up at Martha. "You seem quite at home."

"If anyone got me used to fighting, it's you two," Martha told them.

"Oh, right, so it's our fault?" Jessie quizzed.

"Well, you got me the job," Martha retorted. "Besides, look at me. Am I carrying a gun?"

The Doctor shrugged. "Suppose not," he admitted.

"It's all right for you," Martha told them. "You can just come and go, but some of us have got to stay behind. So I've got to work from the inside, and by staying inside, maybe I stand a chance of making them better."

"Yeah?" the Doctor asked with a grin. "That's more like Martha Jones!"

"I learned from the best."

He smirked. "Well - "

"Although, since she does carry a gun," Martha began in a teasing voice.

"Oi!" the Doctor whined, and Jessie and Martha doubled over laughing.

"Oi, you lot!" Donna told them as she reentered with Steve, Mace trailing a little bit behind, holding something behind her back. "All your stormtroopers and your sonics. You're rubbish! Should've come with us."

"Why?" the Doctor asked. "Where have you been?"

"Personnel," Steve replied.

"That's where the weird stuff's happening, in the paperwork," Donna explained. "Because I spent years working as a temp. I can find my way round an office blindfold, and the first thing I noticed - " She pulled the thing out behind her back, revealing a completely empty binder. "Is an empty file."

"What's not inside it?" Jessie asked.

She smirked, showing them the side. "Sick days!" she answered triumphantly. "There aren't any! Hundreds of people working here, and no one's sick! Not one hangover, man flu, sneaky little shopping trip, nothing. Not ever. They don't get ill."

"And I can vouch for them, they're not all super soldiers," Steve promised.

"That can't be right," Mace muttered, taking the binder.

"You've been checking out the building," Steve told him. "You should've been checking out the work force."

"I can see why they like you," Martha told them with a grin.

"Mmm hmm," Donna replied smugly.

"You are good."

"Super temp."

"Doctor Jones, set up a medical post," Mace ordered. "Start examining the workers. I'll get them sent through."

Martha nodded. "Come on, Donna. Give me a hand."

Donna followed Martha as the Doctor, Jessie, and Steve followed Mace out of the building. "So, this ATMOS thing," Jessie said. "Where'd it come from?"

"Luke Rattigan himself," Mace replied.

"And himself would be?"

He nodded to the screen as they entered the mobile command center, Luke's face on the screen. "Child genius," he replied. "Invented the Fountain Six search engine when he was twelve years old. Millionaire overnight. Now runs the Rattigan Academy. A private school, educating students handpicked from all over the world."

"A hothouse for geniuses," Jessie mused before elbowing the Doctor. "Wouldn't mind going there. How many people there would outsmart you?"

"Oi!"

***

"Do you think I should warn my mum about the ATMOS in her car?" Donna asked Martha worriedly.

"Better safe than sorry," Martha replied.

"I'll give her a call," Donna decided, pulling out her phone.

"Donna," Martha began hesitantly. "Do they know where you are?" She frowned, looking up. "Your family," Martha corrected. "I mean, that you're traveling with the Doctor and the Bad Wolf?"

"Not really," Donna admitted. "Although, my granddad sort of waved us off. I didn't have time to explain."

"You just left him behind?"

"Yeah."

"I didn't tell my family," Martha said softly. "I kept it all so secret, and it almost destroyed them."

"In what way?" Donna asked in a hushed voice.

"They ended up imprisoned," Martha replied simply. "They were tortured. My Mum, my Dad, my sister. It wasn't their fault, but you need to be careful. Because you know the two of them. She's wonderful, he's brilliant, but they're like fire. Stand too close, and people get burnt."

Donna stared at her as Martha nodded and left.

***

"You are not coming with us," the Doctor told Mace firmly as they headed to the outside of the factory. "I want to talk to this Luke Rattigan, not point a gun at him."

"And Steve never has a gun," Jessie added, beaming at her old friend, who smiled back at her.

"But you do," Mace pointed out.

"I repeat. It knocks people out."

"It's ten miles outside London," Mace tried instead. "How are you going to get there?"

"Well, then, get us a Jeep!" the Doctor said impatiently.

"According to the records, you travel by TARDIS."

"Yeah, but if there is a danger of hostile aliens, I think it's best to keep a super duper time machine away from the front lines."

"I see," Mace commented. "Then you do have weapons, but you choose to keep them hid - " He cut off at the "Deathbringer glare" Jessie sent at him, and Steve coughed into his arm, hiding a grin. "Jenkins?" Mace asked, turning to one of the UNIT officers.

"Sir," he replied, straightening.

"You will accompany the Doctor and take orders from him."

"Yeah, I don't do orders," the Doctor replied.

"Ross," Steve greeted with a nod.

"Captain," Ross replied.

"Any sign of trouble, get Jenkins to declare a Code Red," Mace told them. "And good luck, sirs, ma'am." He gave another salute.

The Doctor sighed. "I said no salutes!"

"Now you're giving orders," Mace told him before heading back inside.

"He's getting a bit cheeky, isn't he?" the Doctor asked.

Jessie patted his arm as Donna came up. "Doctor," she began.

"Oh, just in time!" the Doctor told her in excitement. "Come on, come on, we're going to the country! Fresh air and geniuses. What more could you ask?"

"I'm not coming with you," Donna said softly, and Jessie stared at her in surprise. "I've been thinking . . . I'm sorry. I'm going home."

"What?" Jessie breathed.

"Really?" the Doctor asked in just as much surprise.

"I've got to," Donna told them.

The Doctor slowly nodded. "Oh. If that's what you want. I mean, it's a bit soon. I had so many places I wanted to take you. The Fifteenth Broken Moon of the Medusa Cascade, the Lightning Skies of Cotter Palluni's World, Diamond Coral Reefs of Kataa Flo Ko." Jessie was about to add in when she saw the amusement in Donna's eyes, and she slowly turned to look behind her to see Steve watching in just as much amusement before she buried her face in her hands, shaking with laughter. She'd honestly thought that? "Thank you. Thank you, Donna Noble. It's been brilliant," the Doctor continued, still absolutely clueless. "You've . . . you've saved our lives in so many ways. You're - "

Jessie coughed meaningfully, and he looked at her. "Do you need another slap?" she asked.

He blinked at her before turning back to Donna. "You're just popping home for a visit. That's what you mean."

"You dumbo," Donna laughed fondly.

"And then you're coming back," he said, just to make sure.

"Know what you are?" Donna asked, still laughing. "A great big outer space dunce."

"Yeah," the Doctor admitted.

Jessie gasped in shock, grabbing his face and quickly checking him over. "Are you all right?" she asked, mockingly frantic.

"Why?" he asked in confusion and worry, looking over her shoulder at Steve.

"I could have sworn that you just admitted you were an idiot."

He made a face at her and kissed her before Ross cleared his throat from behind them. "Ready when you are, sir," he said awkwardly.

Donna nodded. "What's more, you can give me a lift. Come on."

They headed for the Jeep when Jessie paused. "Hold on a second. Broken moon of what?"

"I know, I know," the Doctor sighed, waving a hand.

Jessie frowned as they got in the Jeep. The Medusa Cascade. That's what he'd said. Evelina had mentioned that, too. What exactly was this huge Medusa Cascade?

***

"I'll walk the rest of the way," Donna told the four of them as they stopped in the middle of the road. "I'll see you back at the factory, yeah?"

"Bye!" the Doctor replied, waving, and Jessie and Steve did, too.

"And you be careful!" Donna told them.

Jessie laughed as the Jeep drove away, and Donna turned and walked down the road. "Haven't seen you for days," a neighbor told her as she walked.

"Yeah, been away," Donna replied when she stopped short, remembering every event she'd been through with her new friends. She started to tear up, and it didn't help when she saw her grandfather only a few yards away, taking out the trash. He looked up and saw her, and he stopped short as well, before he waved at her, and she ran as fast as she could towards him to give him a huge hug.

***

"I said so, didn't I?" Wilf asked triumphantly when they were at the table. "Aliens! I said they was real! I just didn't expect them in a little blue box."

"It's bigger on the inside," Donna said with a grin.

"Yeah, but is it safe? This Doctor and his wife, this Bad Wolf, are you safe with them?"

"They're amazing, Gramps," Donna sighed. "They're just . . . dazzling." She pointed at him. "And never tell either of them I said that. Well, maybe his wife. Then she could brag to him about it. I swear, those two are adorable."

"No," Wilf replied.

"But I'd trust them with my life!"

"Hold up. I thought that was my job!"

"You still come first," Donna assured him.

"Well, for God's sake, don't tell your mother."

"I don't know." She put her chin in her hand. "I mean, this is massive! Sort of not fair if she doesn't know."

"Doesn't know what?" Speak of the devil, Donna thought with a groan as her mother came in with the laundry. "And who's she, the cat's mother? And where've you been these past few days, after that silly little trick with the car keys? I phoned Veena, and she said she hadn't seen hide nor hair."

"I've just been traveling," Donna replied.

"Oh, hark at her, Michael Palin," Sylvia said sarcastically. "Are you staying for tea, because I haven't got anything in. I've been trying to keep your granddad on that macrobiotic diet, but he sneaks off and gets pork pies at the petrol station." Wilf blinked and opened his mouth to protest, but Sylvia shook her head at him. "Don't deny it. I've seen the wrappers in the car. Oh, I don't miss a trick." She turned to Donna. "Now, then. What were you going to tell me? What don't I know?"

Donna sighed. "Nothing," she replied, shaking her head. "Just . . . nothing."

"Good. Right, then, you can sit there and cut out those coupons. Every penny helps. This new mortgage doesn't pay for itself. Dad, kettle on."

Wilf winked at Donna, holding a finger to his mouth before he replied. "Yeah. Kettle on."

Donna smiled gratefully at him.

***

"UNIT's been watching Rattigan Academy for ages," Ross explained as they drove on the grounds of the Rattigan Academy. "It's all a bit Hitler Youth. Exercise at dawn and classes and special diets."

"Turn left," the ATMOS device told them.

"Ross, one question," the Doctor spoke up. "If UNIT thinks that ATMOS is dodgy - "

"Go straight on."

"How come we've got it in the Jeeps?" Ross guessed. "Yeah. Tell me about it. They're fitted as standard on all government vehicles."

"Except SHIELD," Steve interrupted. "We've . . . sort of got a pass."

"Lucky SHIELD," Ross told him. "We can't get rid of them till we can prove there's something wrong."

"Turn right."

Ross smirked. "Drives me around the bend."

Jessie groaned as Ross did just that, drive around the bend. "Dear God almighty," she muttered.

The Doctor just grinned and laughed. "Oh, nice one!"

"Timed that perfectly," Ross said happily.

"Yeah," the Doctor agreed. "Yeah, you did."

"This is your final destination."

Jessie jumped out of the Jeep, looking around with her hands in her trench coat pockets. "Is it PE?" she asked as they took in all of the students doing laps around the building.

"I wouldn't mind a kick around," the Doctor commented as they walked up to the teenage boy standing absolutely still, obviously like he was waiting for someone. "I've got me daps on."

"'Course, I think Steve would beat both of us in the long run," Jessie joked.

"Oh, another nice one!" the Doctor praised, giving her a hug.

"I suppose you're the Doctor?" Luke asked.

"Hello!" he replied with a wave.

"Your commanding officer phoned ahead."

"Funny," Jessie said, wrinkling her nose. "I don't remember calling you."

"She's my only commanding officer around here," the Doctor told him with a smirk. "Why, have you got one?" He pointed. "Oh, and this is Ross and Steve. Say hello, Ross and Steve?"

"Good afternoon, sir," Ross greeted politely.

"Hi," was all Steve said.

"Let's have a look, then," the Doctor said as they headed inside. "I can smell genius!" He paused. "In a good way."

***

"Oh, now that's clever," the Doctor said, running up to something in the laboratory. "Look! Single molecule fabric. How thin is that?! You could pack a tent in a thimble!"

"Gravity simulators!" Jessie added across the room, investigating on her own. "Terraforming, biospheres, nano-tech steel construction!"

"This is brilliant!" the Doctor cheered before sobering and turning to Luke. "Do you know, with equipment like this, you could . . . oh, I don't know . . . "

"Move to another planet?" Jessie asked.

"Or something, yeah."

"If only that was possible," Luke told them.

"If only that were possible," the Doctor corrected. "Conditional clause."

Luke fumed. "I think you'd better come with me."

***

"You're smarter than the usual UNIT grunts, I'll give you that," Luke told them as they entered the recreation room.

The Doctor blinked and turned to Ross. "He called you a grunt!" He pointed at Luke. "Don't call Ross a grunt. He's nice. We like Ross." He turned in a circle. "Look at this place!"

"What exactly do you want?" Luke asked.

"I was just thinking, what a responsible eighteen year old, inventing zero carbon cars? Saving the world."

"Takes a man with vision."

"More with blinkered vision," Jessie snorted.

"Because ATMOS means more people driving. More cars, more petrol End result, the oil's going to run out faster than ever. The ATMOS system could make things worse."

"Yeah? Well, you see, that's a tautology," Luke threw in his face, and Jessie looked at Steve in confusion. "You can't say ATMOS system because it stands for Atmospheric Emissions System. So you're just saying Atmospheric Emissions System system. Do you see, Mr. Conditional Clause?"

"Can it, kid," Jessie snapped. "How long's it been since anyone said no to you?"

Luke glared at her in arrogance. "I'm still right, though."

Jessie was ready to jump him had Steve not taken her by the arm, but the Doctor merely nodded. "Not easy, is it? Being clever? You look at the world and you connect things, random things, and think, why can't anyone else see it? The rest of the world is so slow."

Luke nodded. "Yeah."

"And you're all on your own."

"I know."

"But not with this," Jessie spoke up, heading over to the transmat in the corner. "Because there's no way you could've invented this, not single handed. Possibly Earth technology, but really, this is like finding a cell phone in the Middle Ages."

"No, no, it's like finding this in the middle of someone's front room," the Doctor corrected. "Albeit . . . it's a very big front room," he conceded, looking around.

"Why? What is it?" Steve asked.

"Yeah, just looks like a thing, doesn't it?" the Doctor asked as Jessie stepped inside, looking around. "People don't question things. They just say, oh, it's a thing!"

"Leave it alone!" Luke ordered.

"You know, we're clever too, Luke," Jessie told him, looking around. "We make connections. And currently, to me, anyway . . . I'm thinking . . . teleport!"

"Be careful!" the Doctor shouted as she slammed her hand down on a button close by.

She materialized on a dark spaceship. "Orbit now holding at five five six point three, sector two seven zero."

Jessie's jaw dropped when she saw potato-like aliens in battle gear turn to her. "Oh," she said weakly.

"We have an intruder!" the obvious leader declared.

"Oh, well," she stuttered, "how did she get in? In tru da window?" She grimaced. "Oh, now I'm turning into him," she grumbled before waving. "Bye bye!" She slammed the button again, sending her back.

She quickly ran out. "Get out!" she shouted. "We need to get out of here, now!"

But before she could get to the controls, the same alien who had found her before teleported in. "Sontaran!" the Doctor declared. "That's your name, isn't it? You're a Sontaran. How did I know that, hey? Fascinating, isn't it? Isn't that worth keeping me alive?"

"I order you to surrender in the name of the Unified Intelligence Taskforce," Ross ordered, aiming his gun as Steve braced himself for a fight.

"That's not going to work," Jessie told them. "Cordolaine signal with a copper excitation stopping the bullets."

"How do you know so much?" the Sontaran asked suspiciously.

"Well," the Doctor drawled out.

"Who is he?" the Sontaran asked, turning to Luke.

"He didn't give his name," Luke replied.

"But this isn't typical Sontaran behavior, is it?" the Doctor asked. "Hiding? Using teenagers, stopping bullets? A Sontaran should face bullets with dignity. Shame on you!"

"You dishonor me, sir!" the Sontaran shouted.

"Yeah? Then show yourself!"

"I will look into my enemy's eyes!" the Sontaran declared, taking off his helmet.

Steve's eyes widened. "Oh, my God," he whispered.

"And your name?" Jessie asked.

"General Staal of the Tenth Sontaran Fleet. Staal the Undefeated."

"Oh, that's not a very good nickname," she snorted. "What if you get defeated? What, does it change to Staal the Not Quite So Undefeated Anymore But Never Mind?"

"Nice one," the Doctor told her.

"He's like a potato," Ross said blankly. "A baked potato. A talking baked potato."

"Don't forget walking," Steve added.

"Now, Ross, Steve, don't be rude," the Doctor told them. "You look like pink weasels to him."

"You know, I've heard of the Sontarans," Jessie said thoughtfully, picking up a tennis racket and ball and tried her luck at bouncing the ball on the racket, and she nodded when she kept her coordination, then tried to keep talking at the same time. "I've always heard they're the finest soldiers in the galaxy, dedicated to a life of warfare. A clone race grown in batches of millions with only one weakness."

"Sontarans have no weakness!" Staal told her.

"No, I think it's a good weakness."

"Aren't you meant to be clever?" Luke snapped. "Only an idiot would provoke him!"

"Oh, my wife is very clever, don't think otherwise, Luke," the Doctor warned with a growl. "She is very, very clever because what I know, she knows. Therefore, she knows that the Sontarans are fed by a probic vent in the back of their neck. That's their weak point. Which means they always have to face their enemies in battle. Isn't that brilliant? They can never turn their backs."

"We stare into the face of death!" Staal told him.

"Yeah?" Jessie asked, raising an eyebrow. "Well, stare at this!" She held up the ball. "Game point," she joked before serving the ball hard into the back of the teleport, which boomeranged back and hit the back of Staal's neck. He roared in pain, sinking to his knees. "Game!" she cheered.

"Run!" the Doctor shouted, and they ran for the doors and to the Jeep.

***

"Greyhound Forty to Trap One," Steve was saying into the mic. "Repeat, can you hear me? Over."

"Why's it not working?" Ross asked.

"Must be the Sontarans," Jessie replied. "If they can trace that, they can isolate the ATMOS."

"Turn left."

"Try going right," the Doctor said.

"It said left!" Ross told him.

"I know. So go right."

Ross tried the steering wheel, but the wheel never turned. "I've got no control," he said in shock, letting go, and the Jeep still drove itself. "It's driving itself! It won't stop!"

The Doctor and Jessie tried to sonic the doors, and she shook her head. "Why does everything have to be deadlocked?" she grumbled as he tried the ATMOS next.

The Doctor shook his head. "ATMOS is, too," he said. "I can't stop it!"

"Let me," Ross said, trying to yank the ATMOS device off.

"Turn left."

"The sat-nav's just a box, wired through the whole car!" the Doctor told them.

"We're headed for the river!" Steve warned.

Jessie suddenly got an idea. "ATMOS, are you programmed to contradict our orders?" Jessie asked.

"Confirmed."

"So anything I say, you'll ignore it?"

"Confirmed."

"Then drive into the river!" she ordered, to the shock of the men in the car. "I order you to drive into the river!" The Doctor suddenly got it and laughed. "Do it! Drive into the river!"

The Jeep stopped just inches away from the river bank, and Jessie quickly got out of the side door with Steve, the Doctor and Ross out the other way. "Turn right, left," the ATMOS was saying.

"Get down!" the Doctor ordered.

Steve grabbed Jessie and pulled her to the ground. "Left, right, left, right, left, left, right, left right - "

There was a small bang and a pop, and Jessie poked her head up, looking at the smoking ATMOS device. "Aww, that was it?" she whined.

The Doctor laughed and ran to her, pulling her up, and they quickly headed for the streets.

***

Jessie knocked on Donna's door as the Doctor went to investigate their car. Donna opened it, and Jessie sighed, holding up the tennis racket she belatedly realized she had still hung onto. "You would not believe the day we're having," she said with a laugh, tossing the racket off to the side.

"I'll requisition us a vehicle," Ross was saying as she and Donna joined the Doctor.

"Anything without ATMOS," the Doctor requested. "Steve, make sure he doesn't point his gun at people."

Steve nodded, and the two of them left as an old man that looked familiar came out of the house. "Is it them?" he asked. "Is it them? Is it the Doctor and the Bad Wolf?"

Jessie blinked as she got a good look at him. "Hey, I recognize you!"

"You what?" the Doctor asked, poking his head up from what he was doing.

The man's eyes brightened. "Ah, it's you two!"

"Oh, it's you!" the Doctor said, straightening with a grin.

"What?" Donna asked, looking back and forth between the three of them. "Have you met before?"

"Yeah, Christmas Eve," the man replied. "They disappeared right in front of me."

"And you never said?!"

"Well, you never said," he pointed out before holding out a hand and grinning at them. "Wilf, sir, ma'am. Wilfred Mott. You must be some of them aliens."

"Yeah, but don't shout about it," the Doctor warned, but shook his hand. "Nice to meet you properly, Wilf."

"Without us disappearing on you," Jessie added with a laugh.

"Oh, alien hands," Wilf commented.

"Donna? Anything?" Jessie asked as Donna tried calling Martha.

"She's not answering," Donna replied. "What is it, Sontorans?"

"Sontarans," the Doctor corrected. "But there's got to be more to it. They can't be just remote controlling cars. That's not enough. Is anyone answering?"

"Hold on," Donna replied, holding up a finger and pausing before saying, "Martha. Hold on, they're here."

The Doctor took her phone, putting it between his and Jessie's ears. "Martha, tell Colonel Mace it's the Sontarans," he ordered. "They're in the file."

"It's under Code Red, Sontarans," Jessie added. "But if they're inside the factory, tell them not to start shooting. UNIT will get massacred. We'll get back as soon as we can."

"You got that?" the Doctor asked.

"Code Red Sontaran," Martha's voice replied, and Jessie's eyes narrowed a little bit. "Gotcha."

"That didn't sound like her," she told the Doctor as Martha hung up.

"I know," the Doctor replied, tossing Donna's phone back to her and popping the front end of the car open.

"But you tried sonicking it before," Donna told them. "You didn't find anything!"

"Yeah, but now I know it's Sontaran," the Doctor told her. "I know what I'm looking for."

"The thing is, Doctor, that Donna is my only grandchild," Wilf told them. "You got to promise me you're going to take care of her."

"You're kidding me, right?" Jessie laughed. "She takes care of us!"

"Oh, yeah, that's my Donna," Wilf said appreciatively, patting her shoulder. "Yeah, she was always bossing us round when she was tiny. The Little General, we used to call her!"

"Yeah, don't start," Donna warned.

"And some of the boys she used to turn up with," Wilf continued. "Different one every week. Hey, who was that one with the nail varnish?"

"Nail varnish?" Jessie laughed.

"Matthew Richards," Donna spat out. "He lives in Kilburn now. With a man."

"Hi ho!" Jessie exclaimed, jumping back when spikes shot out of the ATMOS device.

"Whoa!" the Doctor exclaimed as well as Donna's mother came out of the house. "It's a temporal pocket! I knew there was something else in there! It's hidden just a second out of sync with real time."

"But what's it hiding?" Donna asked.

"I don't know, men and their cars," her mother commented as she joined them. "Sometimes, I think if I was a car - " She stopped short, seeing who was there.

"Oh, great," Jessie sighed. "Sylvia Noble. Oh, how our days keep going."

"Sweetheart, that's rude," the Doctor admonished.

"Well, I'm not ginger, am I?" she teased, and he winked at her.

"Oh, it's you two," Sylvia spat. "Doctor what was it? And Bad Wolf?"

"Yeah, that's us," the Doctor said absently, waving as he investigated more.

"What, have you met them as well?" Wilf asked.

"Dad, it's the two from the wedding," Sylvia replied. "When you were laid up with Spanish flu. I'm warning you, last time those two turned up, it was a disaster."

"Get back!" the Doctor shouted as gas began to come off of the spikes.

Jessie pulled out her sonic and got to work with him. "That should stop it," she panted, making one last adjustment and wincing at the "bang!" that was let off.

"I told you!" Sylvia crowed. "She's blown up the car! Who are they, anyway? What sort of people blow up cars?"

"Oh, not now, Mum!" Donna groaned.

"Oh, should I make an appointment?" Sylvia asked.

"Well, he is a doctor," Jessie told her, flipping her screwdriver up. "Most of his appointment slots are taken up, though."

"Really?" the Doctor asked, looking at her. "By who?"

"Me," she replied cheekily, giving him a saucy grin.

His eyes darkened and he gave her a searing kiss that made her quite a bit breathless before he pulled back and went back to the car. "That wasn't just exhaust fumes," he told them as Wilf looked back and forth between them, as if stunned by that little show of affection, while Donna just smirked, looking like she was trying not to laugh as Sylvia went back in the house. "Some sort of gas. Artificial gas."

"And it's aliens, is it?" Wilf asked. "Aliens?"

"But if it's poisonous," Donna said slowly, looking around the block. "Then they're got poisonous gas in every car on Earth!"

"It's not safe," Wilf said, opening the driver's door. "I'm going to get it off the street."

The door closed, and there was the click of a lock, and the engine started, and Jessie's eyes widened as gas started flooding the inside of the car. "Hold on!" Donna shouted as Jessie ran to the back of the car, trying to see what was going on. "Turn it off! Granddad, get out of there!"

"I can't!" Wilf yelled through the glass. "It's locked! It's them aliens again!"

"What's he doing?" Sylvia asked, coming out again. "What's he done?"

"They've activated it!" the Doctor replied, spinning around as gas began to flow from every car on the block.

"There's gas inside the car!" Donna told them. "He's going to choke! Doctor!"

"It won't open!" the Doctor told her, yanking on the door handles as he looked around. "It's the whole world."

"Help me," Wilf choked out.

Jessie ran to the front of the car and began yanking at wires, but the gas didn't stop. "Get me out of here!" Wilf said breathlessly before he began to slump.

"Doctor!" Donna sobbed helplessly.

Jessie turned to look around as gas continued to fill the air as the Sontarans began whatever they were planning, and she shook her head. Today will definitely be the day General Staal the Undefeated becomes General Staal the Defeated, she promised. Today.

***

I hope you liked this! "The Poison Sky" is in progress, and I will tell you this, Steve will be on the TARDIS for "The Doctor's Daughter." :) And from there, it's "The Unicorn and the Wasp," and then . . . oho, I have big stuff planned for "Silence in the Library"/"Forest of the Dead." >:)

"The Poison Sky" is coming up soon!