From the top of the van, Henna could see far in either direction while Cas had her head ducked under the hood of the engine. The clack and ratcheting of tools drifted up to her as she looked through the scope on the rifle, keeping her eye on those Screamers still sat in unmoving vehicles around them. They had had no choice but to stop as the engine chugged and gurgled to a barking end.

They had left the horde far behind, but the performance of the tac-van had become more and more pitiful as they had taken turns driving. If nothing else, Cas had managed to catch up with a little sleep, though they still had a few kilometres to go. Or so Cas had said. When asked what it was in miles, Cas had shrugged, either not knowing or not bothering to say.

"Have you found out the problem?" They hadn't stopped for too long, she assumed, but the Screamers didn't appear to have a set amount of time it took for them to sense Cas' presence. "We should keep moving."

"It's the gas. I'm surprised we managed to get this far." More clattering came from below and a hose spun through the air as Cas tossed it away. "It's oxidising, clogging up the fuel lines. Dirty. Gas doesn't last forever."

Henna had no idea about that. Before Cas had even opened up the engine, she had rushed around, searching for trucks, busses, anything with engines of a similar type, tearing out bits and pieces of those engines that she could. They had stayed in communication over the radios in the highway cop helmets, but Henna had worried every time Cas had moved out of her sight.

She felt a tightness in her gut at every movement. Birds catching her eye as they wheeled and turned in the sky, oblivious to what had become of the humans below them. Feral dogs, running in packs, crossing the fields, chasing themselves, or some other animal, desperate for food that their former families could no longer provide. She swore she had seen a bear, strolling along the edge of the woods not far from where the van had come to a stop. She had never seen a bear in her life.

Of people, those that hadn't tilted their heads back to scream incessantly, she saw none. Not a single person. She began to wonder whether she and Cas were the only ones not screaming any more. The group back at the clearing had come under attack from the great mass of Screamers, but she hadn't waited to see if anyone had survived. They were in the past, now. Gone. Maybe dead. She couldn't waste energy feeling pity for them and that turned her stomach. A lot of things did that now.

"Earlier, you said something about 'them' listening in to that radio frequency." She shifted her position, turning to survey a different area around them. "What did you mean? Do you think someone did this? Were we attacked? The Chinese? Russians? Before the news stopped, I thought they said it was worldwide."

Cas said nothing for a long while, except to curse at something in the engine. The van shuddered as Cas wrenched at something that remained stubbornly attached, sending Henna's view through the scope bouncing from where she looked. She'd never used a rifle before and had a good idea she stood no chance of hitting anything with it, but someone had to keep watch. If more scavengers tried to take what they had, or Screamers began to move, she could only give off warning shots, at best.

"There was talk. The usual scuttlebutt, you know. I heard some guys saying North Korea had done it. Fuck knows what those guys are doing in their shithole of a country. Arabs, maybe. ISIS." Cas dropped something and the clatter rattled through the radio. "But it was when I reached the US. I called up on that frequency and got a location, but when I got there, the whole place had become overrun. The Screamers hadn't moved because of me and this thing. They'd attacked independently."

"Shit, Cas! That changes everything! Why didn't you say they could do that?" Timing the Screamers' movements meant nothing now. Thanks to Cas' hoarding of information, Henna had been thinking they were safe for a short time. "God! If they don't need to sense you, they ... That military camp! They just left! Was it the Screamers?"

"Maybe. There's too much we don't know and the best every nation has to offer have learned so little. We're still flying blind after six months." She fell silent, not even attending to the engine, and Henna could imagine Cas touching that package on her chest. "Except for this. I don't even know what it is. It's sealed. I think it's a thumb drive, or something, with the latest information. Those special forces guys certainly thought it more important than their own lives."

Something moved, a little down the road and Henna tried to zero in the scope to that spot but, when she began to scan the area, she saw nothing. It would make no sense if a Screamer sensed Cas from that distance, and not from one of the occupied vehicles nearby, but little made sense in this world anymore. Nevertheless, she continued to watch that area.

Below, she heard Cas turning over the engine, but it stuttered and grumbled instead of catching. Another curse escaped Cas' lips and Henna heard a booted foot connect with the body of the van before Cas sighed, returning to her task. If she needed to do more than replace pipes and hoses, it would involve using a garage, but to do that, they would have to find one and get there. She began to think about how much of their supplies and weapons they could carry if they needed to walk.

Another movement, this time from away in the direction they needed to go, the peaks of mountains peeking up above the towering firs ahead. Again, as she whipped the rifle around, she saw nothing moving, but now she began to pay attention to the Screamers nearby. If some Screamers had sensed Cas and that package, it wouldn't be long until more did. It wouldn't be long until every Screamer on this highway began to turn Cas' way.

"Cas, I think we're out of time." Henna had started to swing the rifle in several directions, seeing more and more movements. Not dogs, birds or bears this time. "You need much longer?"

"I think ... I think I can make it work. I just need a few more minutes." The clanking and ratcheting restarted with a vengeance, the van wobbling from Cas' ministrations. "Just ... just do what you can, okay?"

A car, not far away began to sound its horn and Henna knew they were out of time. Training the scope on the car, she saw a Screamer thrashing about in the seat, scrabbling at the seat belt it wore, hammering against the glass of the door window. It wasn't the only one. So far, all of them appeared trapped in their vehicles, but if Screamers could open locked doors on a sub, they could detach seat belts and open car doors.

"Give me the thing." She had already started to clamber down from the top of the van. "Give it to me. I'll lead them away while you finish fixing the engine."

"No." Somehow, that didn't sound like a 'no' coming from worrying about Henna. It sounded too stern for that. "This is sensitive material. Top secret. I can't allow it out of my sight."

"Who's going to know? The Chiefs of Staff? The President? The FBfuckingI?" Henna tossed the sniper rifle into the back, reaching in for a shotgun instead. She cycled a shell into the chamber. "Just give it to me. I promise, I'll give it back and I won't look at it. They're coming, Cas, and we need this van!"

She moved away, looking for a car that didn't have a Screamer inside and found an old pick-up truck. Like something from an old tv series, or a movie. She half expected the keys to fall into her hand as she tipped down the visor, but saw them dangling in the ignition. The owner had left in a hurry, it seemed. It took a few attempts, but the engine fired up and rumbled to life. These old trucks were built to last and she doubted a little dirty gas would bother it too much.

"Give me the package!" With the old truck idling, she returned to Cas, her eyes switching in all directions. She had no time for Cas to play dutiful soldier. "Fucking give it to me, now, or I'll shoot you in the leg and take it!"

She raised the shotgun and Cas straightened up, her tank top streaked with oil and grease, as were her arms and face. The protruding package between her breasts looked out of place. She leaned her elbow against the tac-van, studying Henna, noting the lack of tremor in the barrel. After a second, she nodded, taking a cloth from the edge of the engine and wiping her dirty hands.

"No, you wouldn't. But I appreciate the threat. I bet you've wanted to do that for years." With a sigh, she tugged the tank top out, rummaging her other hand underneath and winced as she tore the package from her skin. "You're right. We do need this van. Don't do anything stupid. As soon as that truck reaches half the gas it has left, you come the hell back! And, Henna, if you do steal this from me, I'll kill you."

She gave Henna a wink, tossing the package across to her before turning back to the engine. It seemed so incongruous, the simple act of ducking her head into the guts of the tac-van, as though god knew how many Screamers were on their way to tear her apart. For this package. Even as she ran back to the old pick-up, she turned the package over in her hand. The tape rolled back on to the package, but it didn't seem important, or worth the lives of all the people who had struggled to get it this far.

She shifted the truck into gear, tucking the package inside the tactical vest she had worn since the precinct, the shotgun across her thighs. It wasn't worth all those lives. It couldn't be. It certainly wasn't worth Cas' life. Yet, if it did contain something that could put an end to all this, would it be worth it then? Henna didn't know. She only knew that, right now, she had to take on Cas' burden and, as she sped past the first Screamer sprinting their way, she hoped it was the package they sought. Otherwise, this was going to be a short drive.