Kirby fidgets in place as Donatello steps back from April for the umpteenth time. The redhead leans closer to the turtle, his eyes wide.

"Any luck, Donatello? Anything?" he asks.

Donatello shakes his head. Both of them slump, defeated, and Kirby reaches out to take April's hand. The laboratory door slides open and Leonardo looks up. Diaval steps out of the opening, allowing Master Splinter to enter as well. He moves along at a hobbling gait even with his staff in hand, Diaval lingering at his side.

"Sensei, what are you doing? You should still be resting," Leonardo scolds, his face immediately flooding with worry as he rushes to them. "Diaval, you were supposed to help—"

"Got something t'help April," Diaval interrupts. He looks over at Splinter. "Right, Sensei?"

Splinter nods and pulls a bound scroll from his kimono. "April is in grave danger, but I believe that this will help her." He unrolls the scroll, revealing Japanese calligraphy. "It is an ancient poison-draining mantra."

Leonardo's phone rings. He nods curtly to the taller men before him as he slips the device from his belt and checks it. Raphael's caller ID lights up the screen. He answers and puts it to his ear.

"Raph? Where are you?" he asks. There's silence and his hand tightens. "Raph?"

"Hello, Leonardo. Your brothers are right here...with me," says a smooth, feminine voice.

His heart clenches and for a moment, he can hardly speak. It can't be... "Karai? Is...is that you?" he asks.

"Though, they don't appear to be in the best of health," Karai continues. "I'm afraid that if you and Donatello don't come soon, then Raphael, Michelangelo, and Casey Jones will all expire." She whispers the last word very closely into the receiver, sending a shiver up his spine. "Oh, and if Destiny gets back to you, bring her along. She managed to escape." Karai pauses, as if waiting for a reaction, and when none comes she continues, "Come to the old abandoned Greenwich street station. I'll be waiting."

She hangs up. Leonardo shakes the phone, his eyes widening. "Karai? Karai!"

Diaval moves closer to Leonardo. His eyebrows furrow. "Is Karai okay? What happened?"

"She's not getting any better!" Kirby shouts. Both boys turn to find him glaring daggers at Donatello. "I brought her here because I thought you could save her!"

"Calm down, you two," Leonardo orders. "We have another problem."

"There is no other problem. April is the only thing you should be worried about!" Kirby exclaims.

"I'm doing my best, Mr. O'Neil," Donatello says. There's sweat beaded on his forehead, the stress of the situation getting to him.

"Silence! All of you!" Splinter barks. He hobbles to the table, his wise gaze sweeping over the others. "If I can focus, I may be able to get the poison out of her system."

"Kirby, Diaval, stay here. Help Master Splinter with whatever he needs," Leonardo says. He motions to Donatello. "Come on, Donnie. You're with me."

"Wait," Diaval says, reaching out to the brothers. "You said Karai. If she's in trouble—"

Leonardo shakes his head. "Karai isn't in trouble, Diaval. She..." He purses his lips. "She is the trouble. It's better for you to stay out of it."

"But—"

"Let's move, Donnie. No time to lose."

"Leo, can you please explain what's going on?" Donatello asks.

"I'll talk on the way," comes the swift reply.

They disappear from the lab. Diaval stares after them, unmoving, and only Splinter's voice calling for his aid gets him to walk away.

-----------

Donatello and Leonardo get only a couple of feet down the tunnels before they hear a crash and the sound of something heavy collapsing. They ready their weapons without a word and creep towards the noise. Leonardo pokes his head around the corner, prepared for anything, but the only thing in the tunnel is Destiny. She kneels on the tracks, dry, wheezing coughs escaping her. She keeps gritting her teeth and straining. Paws appear over her feet and hands, but disappear after a second and she curses.

"Des!" Leonardo calls. Behind him, Donatello's eyes widen. The two of them emerge from their hiding spot and jog towards her.

Her head drags upwards, her eyes sparking past the cloud of exhaustion. "Guys...Raph, M-Mikey, Casey...a-are—" she wheezes.

"Taken by Karai, we know," Leonardo says.

Donatello kneels and helps her to her feet, her chest still heaving as she brushes her sweaty curls from her eyes. "What?" she asks. "How...how'd you know?"

Leonardo sighs and the tips of his fingers move to the edge of his phone. "She called."

She exhales and droops, bracing her hands against her knees. "I was too late. Shell..."

"You can't change anything now," Donatello says, patting her back. He eyes Leonardo, grave. "We need to go. Where did Karai ask to meet?"

"The abandoned Greenwich street station," Leonardo answers. "Des, you—"

"I can get us all there, fast," she interrupts. "Hold on, I'll just—" She screws up her face, muscles tightening, and a few tufts of fur sprout along her back and arms before disappearing. She exhales one long breath before sucking in another. "Crap, one second. I'll—"

"Des, you're exhausted," Donatello says. "If you strain yourself further, you'll get hurt."

Before she can disagree, Leonardo cuts in. "Grab the Turtle Racer and take the tunnels leading to the station. Donnie and I will take the sewers. You wouldn't be able to hold your breath long enough to come with us anyways."

She doesn't smile, nod, or give any indication that she likes the plan. She straightens up and gives them both swift looks. "Be careful," she says. She brushes past them, en route for the lair, and they continue on without her.

-----------

Leonardo and Donatello emerge from a pool of water into a damp cavern. The only spot of light in the entire place comes from a manhole cover far above, a rusty ladder fastened to the wall right beneath the pillar of light. They right themselves and wade through the waist-deep water towards the ladder.

"Ugh, this water smells extra nasty," Donatello says, his nose wrinkling.

Leonardo gives no response to the comment as he grabs onto the nearest rung and starts to climb. "Come on. This is the way," he urges.

Donatello goes to follow his brother, but when he reaches for a rung, it bends and bows before his eyes and he has to pause to take a few breaths. His head pounds. "I...I don't feel so good," he groans.

Leonardo stops climbing and looks up. The manhole cover above him has started to swim in his vision, going in and out of focus. "Me..." He shakes his head and blinks. "...neither."

They reach the top, pushing aside the manhole and emerging into a tunnel at the pace of non-mutant tortoises. An echoing voice reverberates through the spacious expanse, making the boys wince.

"Leonardo and Donatello," Karai calls. "Sneaky, coming from the sewers." There's a laughing tone to her voice that sets the two terrapins on edge, but they don't stop walking. "How are you feeling, turtles? Nauseous? Dizzy?"

Leonardo tries to force back those exact feelings even when he feels as if his brain and head is stretching and contorting as if they're made of putty. Donatello moans and grips his head, squeezing his eyes shut.

"My brain is...melting."

Leonardo looks at Donatello, but he no longer sees a turtle. Instead, he sees a turtle body with a pineapple head on it. There's a purple mask surrounding pale, unblinking white eyes and a fork is strapped to the pineapple-turtle's shell instead of a bō staff.

"Dude, why do you have a pineapple for a head?" he demands, pointing at his brother's new features.

"We've been...poisoned," the former responds with an air of fear in his fruity countenance.

"Oh," Leonardo groans as the two of them break into a sprint. "We have to act fast."

They dash down the tunnel, panting more and more with each stride as their energy saps away like water through a leaky tap. Karai's voice surrounds them again.

"My venom is highly toxic in any form, even in water," she informs them, her amusement still evident. A serpentine shadow appears on the far wall before it shrinks down to a human shape. "It seeps through the skin in seconds."

Leonardo and Donatello can finally see her, waiting for them with a hand resting on her hip and a smirk on her ruby red lips. Her luminescent skin seems to glow even in the yellowed lights of the old tunnel and her eyes, once the colour of caramel, are acid green. Dangling from the rafters behind her are Raphael, Michelangelo, and Casey. Donatello slows almost to a complete stop as he coughs, clutches his chest, and collapses. His plastron clunks against the iron rails as Foot bots surround him from behind and Leonardo, determined, unleashes a single katana and hobbles towards his older sister.

"It's over, Leo," she hisses.

His vision swims, the Foot Clan members before him blurring and wiggling as if he's looking at them through a trembling water glass. His eyes roll back in his head as his fingers go limp and he pitches forward, landing beside his fallen brother as a rush of air leaves his lungs.

"You and your friends are finished," Karai murmurs.

Foot bots surround the remaining brothers. In a nearby side tunnel, Destiny pulls the Turtle Racer to a stop and cuts the engine. She removes her hockey helmet and climbs out, tucking the headwear on the seat before readying her uchigatana and creeping towards the exit.

She peers out of the tunnel, obscured by shadows, just able to see Karai and her henchman at work. Her fluffy ears flick.

"Finally, after all this time," Karai says, basking in her victory. "Put them with the others. I want to admire my trophies," she says to her bots as they carry Leonardo and Donatello closer to their hanging brothers. "Watch out for Destiny. She'll be here soon."

Destiny doesn't dare move or even breathe too loudly. She tucks her sword close to her side and inhales, shutting her eyes as she tries to listen closer. Soft words reach her, making hope bubble up in her chest when she realizes that only one person could be saying them.

"Rin. Pyo. Toh. Sha."

A sly grin curls across her lips and she grips her sword just a little bit tighter.

"The poison is slow. Within the hour you will all perish," Karai promises as Donatello is set up to hang next to the others. There's a soft clatter from nearby and she turns around to see Destiny standing a few feet away from her. "Destiny," the snake mutant hisses. "It's about time you showed up. Too bad you won't be able to save your precious boys."

"I thought you changed, Karai," Destiny says. "What about your brothers? What about Diaval?"

"I never cared about any of you. You're nothing more than a means to get to Splinter."

Destiny creeps closer. She can still hear Leonardo's soft, exhausted voice breathing out his mantra, "Rin. Pyo. Toh. Sha." His hand shifts and the glint of a knife flashes across Destiny's eyes and she glances his way for a second.

There's a hiss and Karai's serpentine hands fly at her. Destiny throws her sword up for a block, but it's weak and flimsy. The snakes' mouths close around the blade and promptly snap it in half. Her eyes widen and Karai lets out a menacing hiss, her forked tongue flicking between her lips.

"Oh shell," Destiny mutters.

The snake hands zip towards her and she grits her teeth. She keeps backing up, attempting to deflect the blows with the shattered end of her weapon, but it's hopeless. One snake knocks the broken handle from her grip while the other latches around her shoulder. She stiffens, wobbling, and the second snake head rounds on her and bites into her arm.

There's a grunt and the sound of deactivating Foot bots as Destiny crumples into a sad heap on the ground. Karai turns to see Leonardo standing by the broken, sparking bodies of her henchman. He's holding his side, his shoulders shuddering with his weak breaths.

"Beating the poison. Impressive," Karai says, eyes narrowed.

Leonardo stares at her. His face is twisted with pain. "Shredder...used some kind of brain worm on you."

"Lies won't help you, Leo." Her foot slides back as her shoulders lift. "I'll just have to finish you myself!"

She hisses and races at him. He inhales and poises himself, arms and body at the ready, and she swings her leg at his face. He dodges easily, but she's far from ready to let up. Her arms and legs move in a practiced flurry as the dull thud of his arms blocking the hits resonates in the empty tunnel.

"Karai, you have to fight it," Leonardo says, still engaged in battle.

"Hyah!" she grunts, flinging one snake arm at him.

He avoids the fangs, but the snake boomerangs and wraps itself around his neck while the other arm surrounds his body. He struggles and chokes as Karai lifts him and throws him away, his body bouncing in sync with his grunts as he rolls along the tracks.

He stumbles back to his feet, but the snake heads soar from the shadows and sink their fangs into his biceps. As he stiffens from the poison flooding into his veins, he's yanked forward, pulled right into her feet as she leaps up and smashes him in the chest. He hits a thick, metal support beam shell-first, then hits the ground.

"Still feeling the effects?" Karai asks, her voice echoing in his ears. His muscles burn and his breaths are fast, but his eyes are still open and he's not ready to go down yet. "You're weak, Leo, and you're done for!" Karai snaps.

Somehow, he gets back up and places his hands together in front of him. "Rin. Pyo. Toh. Sha," he murmurs, his voice growing with each word as he forms symbols with his hands. "Kai, jin, retsu, zai, zen. Rin! Pyo! Toh! Sha! Rin! Pyo! Toh!" Another deep breath rolls through him, his energy and power flooding into this one area of focus. "Kai! Jin! Retsu! Zai! Zen!"

Karai's eyes widen as his hands start to glow white. "What are you doing?! What is this?!" she demands.

Leonardo places his hands on his chest, spreading the aura throughout his entire body and creating a mystical halo that surrounds him. His arms fall to his sides. His eyes close. Karai hisses with disdain and sprints towards him. She flings her left snake arm at him, but he dodges and smacks it away with a strong backhand, his eyes still closed.

"Rin!" he grunts as the snake goes limp.

Karai whips her right arm at him, but he dodges that too, moving with the grace of the wind as he sweeps to the side. His forearm hits the serpent and it too falls into unconsciousness.

"Pyo!" he utters through gritted teeth.

Karai twists her body into a graceful, leaping arc, her arms dangling uselessly behind her as she front flips and aims her foot for Leonardo's face. His eyes open and he throws his clenched fist out, catching her foot against it.

"Toh!" His voice is getting stronger and stronger with each movement.

She lands on the rails again, knocked off balance, and Leonardo takes advantage of the moment of weakness. He rushes at her, his fist pressing against her stomach and knocking the wind out of her. She gasps for breath and his eyes go white.

"SHAAAAA!" he bellows.

The shockwave of sound and the impact of the blow sends her flying into a support beam. She exhales, her pale skin getting slightly paler as she slumps forward, defeated.

Leonardo spends no time acknowledging his victory. He moves to his unconscious brothers and Casey and makes quick work of lowering them back to the ground. Slowly and surely, he manages to half drag, half carry them away and place them closer to where Destiny parked the Turtle Racer. He sets Casey down, then walks to Destiny, kneels, and pulls her limp body into his arms. He stands, adjusting his grip on her as he turns around.

"You're coming with us, Karai," he says. His face falls when he notices that the tunnel has been abandoned. His sister is nowhere to be seen. "Oh, Karai..."

-----------

"Rin. Pyo. Toh."

Leonardo and Splinter place their hands on Raphael, Casey, Michelangelo, and Donatello's chests. Diaval, April, and Mr. O'Neil observe from a distance. There's a moment where the healing aura surrounds the resting teens and then, it fades away and their eyes peel open. There's a round of groans as they sit up, some blinking, some gripping their heads, some doing nothing noticeable.

"Man...snakebite is worse than the worst," Casey mumbles.

"Snakebite's not that bad," Michelangelo says in a relaxed tone. He hugs his knees, starting to rock back and forth gently. "I've been bit by giant wasps, mutant dogs, Dream Beavers, squirrels, squirrelanoids—"

"Are you still talking?" Raphael snaps.

Leonardo stands and moves to where Destiny is laying beneath the dojo tree. He murmurs the mantra and rests his hands on her shoulder and stomach. Behind him, tense, worried conversations continue.

"It wasn't really snakes that almost took us out," April says, her lips tugged into a frown. "It was Karai."

"She's back under Shredder's control. He's the one responsible, not Karai," Donatello says. His russet eyes flicker over to Leonardo for a brief moment.

Destiny's eyes open. Her blurred vision slowly comes back into focus, sharpening the details of the turtle above her. Her expression floods with relief and she lurches upwards, engulfing him in a tight hug as she buries her face against his neck.

"You're okay," she whispers. "Not like I ever doubted you."

Leonardo returns the gentle hug, closing his eyes as his hand caresses her frizzy brown curls. He takes a deep breath and she pulls away, her lips pouting with concern.

"Leo?" she asks.

He sighs, but still says nothing. She reaches up, brushing her hand against his cheek as she searches his expression, and he grasps her wrist and pushes it back to her lap.

"I'm gonna go," he tells her. He stands up and leaves the dojo without another word.

Destiny stares after him, and only once he's gone does she notice how quiet the dojo has gotten. She looks over her shoulder to find that the others are also gazing at the exit. Not a single expression is positive.

"Perhaps I should talk to him," Splinter suggests. "I will be back."

Outside, Leonardo stands at the edge of the living room pit, downcast. Splinter descends the steps of the dojo and moves towards his son, his movements as silent as any ninja's should be.

"You should be enjoying your victory," he comments, making the blue-masked turtle turn around, eyes wide. "You did a great thing tonight, Leonardo. You saved everyone."

Leonardo's face falls yet again as he looks to the ground. "Not everyone. I tried to get Karai out of Shredder's control." He squeezes his eyes shut as his fists clench. "I failed, Sensei. I'm sorry."

Splinter watches him for a moment. He's seen him wear that look of hopelessness before and it breaks Splinter's heart. "We saved her once, Leonardo," he murmurs, placing a hand on Leonardo's shoulder. "Perhaps...we can save her again." The rat smiles a little and straightens up, resting both hands on his staff. "And now you show great gifts as a healer. Being at the edge of your life gave you a power that few martial artists can tap. I am proud of you, my son."

Leonardo looks up, the tiniest of smiles lifting his lips, and he feels his heart swell with pride. Raphael, Donatello, Michelangelo, and Destiny walk out of the dojo, Diaval bringing up the rear, and head for the two males.

"Um, Leo, we just wanted to thank you...for saving us," Donatello says, smiling as he rests a hand over his heart.

"Yeah. You kicked Foot bot butt, stopped the poisons, got us out of there, and you did it solo," Raphael says, glancing at the teens around him with an impressed look. "None of us could've done that."

"Well done, captain," Destiny says with a salute.

Leonardo takes a deep breath, resting his hands on his hips. "Maybe you're right," he says, looking up at Splinter. "Maybe tonight was a win."