I threw up my hands. “Jesus Christ, you think you’re playing a computer game! Killing someone does not make you level up! All it gets you is nightmares for the rest of your life and the never-ending hatred of everybody who ever cared about the person you murdered!”

My voice had risen to a shout, and both Lee and Captain America stood staring at me; without looking I knew Anne had turned to do the same. I stood balancing on the train, the wheels rumbling beneath my feet. The futures of Lee and Captain America flickered, shifting. Will’s didn’t, and his eyes stayed steady. “They said you were good at talking your way out of things,” he said. “Not going to work this time.”

I felt Lee and Captain America’s futures waver and then fall into line to match Will’s. I wanted to swear, wanted to keep shouting, but my precognition was starting to sound a warning and I knew we were out of time. “Anne,” I said. “Go. Get down.”

Anne turned and ran, crossing the gap from the fourth to the third carriage with a running jump. I gave Will’s group a last glance and followed, putting a little extra speed into the leap to make sure I cleared it. Up ahead I could see a dark wall with streetlights running along the top of it, and the tracks ran into a black circle. We’d had a long run in the open but London’s a built-up place, and every railway line in the city goes underground sooner or later. In this case sooner or later meant now. As soon as I’d made it onto the third car I dropped and craned my neck back to look.

Will, Lee, and Captain America were staring at us through the forcewall, watching the tunnel entrance draw nearer. I wasn’t close enough to see their expressions but I saw the jolt go through Captain America as he figured it out, and as the tunnel mouth swept over us he yelled a warning and turned to run. Lee followed; Will stayed a little too long and had only just started to sprint away as the fourth carriage passed into the tunnel, and through the shrinking window of the tunnel mouth I had one last glimpse of their backs before the forcewall hit the top of the tunnel and physics took over.

I didn’t get much of a view of what happened next. It was all very fast and my attention was focused on hanging on. Looking back on it with the benefit of hindsight and having read the accident reports, what I think happened was this.