The remainder of the damaged bridge collapsed into the road, leaving just one gap underneath the part blown away by the tank. Mark bit his lip as he found a way through the dust, squeezing through a gap between two cars, a gamble which cost them both wing mirrors. There was an even tighter gap ten metres ahead, between a painter’s van and a petroleum tanker.

The gap between them and the Challenger was closing. Kate gasped as she finally realised the flaw in Mark’s plan: that even if they got close enough to escape its long-range weaponry, and even if the chain gun operator were a useless shot, the tank could just crush them underneath its tracks. In fact, the clones inside might find the experience more satisfying.

The third blast roared from the barrel, but the humans’ lives were saved by bad timing. The tank reached the end of the set of cars underneath it, and dipped forwards. The barrel sank by about ten degrees, sending the third shell several hundred metres too short.

If they’d fired correctly, we’d be dead. A shell anywhere close to the tanker would have done the job.

‘OK, their sight is blocked by the dust cloud,’ Mark said. ‘Get out.’

Simon obeyed as expected. Kate wanted to follow, but her body wouldn’t let her. Mark leapt out of the driver’s seat, and took the time to stare back into the car before closing the door.

‘Kate,’ he said, ‘I’m sorry Raj is dead. He was a nice lad. And I wish we had time for you to go through your I’m-so-sad-my-life-is-over phase. But we don’t. The tank is coming now, so I’ve got this plan and I really hope you can pull yourself together quick enough to be part of it.’

Pull yourself together… that’s what the teachers back in mainstream used to say.

Mental health issues don’t just ‘ pull themselves together ’ Mark, you bloody numpty . You don’t stop grieving by ‘ pulling yourself together ’ . Even now, I don’t know how people do it.

She felt angry, an emotion she had not had the energy for all night. It squeezed itself between her fatigue and her misery, and motivated her to move herself. She huffed as loudly as she could manage, and opened the passenger door.

For a split-second, a small but important realisation entered her brain. One of her therapists had once talked about humans’ ‘fight or flight’ instincts: that when a situation got too much for them, a person would either face it head-on or get the hell out of there.