He stumbled on, every few seconds lighting the way ahead. The tunnel split in two and he made a quick decision, taking the left-hand branch. A little farther along he came to a stopped train. It fitted too tightly in the tunnel for him to squeeze past, so he would have to go underneath.

He dropped onto his belly and crawled under the front of the train, wriggling like a worm. It was hard work and difficult to move without making a noise. Were the grown-ups still following? He shone the flashlight back. There were three of them there, peering under the carriage, their eyes bulging, red and swollen, their tongues lolling. One of them flopped down and started to slither his way forward.

Sam switched off the flashlight.

Blackness again.

He crawled on. His knees stinging. The sound of his followers too close behind.

The one in front worked his way nearer and nearer, his rancid breath coming in short rasping gasps. He got hold of Sam’s ankle. Sam kicked out and kept kicking. He felt something break like a twig, and he hoped it was at least a finger. No matter how hard he kicked it, though, the grown-up wouldn’t let go. It was then that Sam remembered the butterfly pin. He had it stuck through a fold of cloth on the front of his sweatshirt. He pulled it loose, curled back around, and struck—jab, jab, jab, jab, jab—right where he thought the grown-up’s face would be. It was like poking a watermelon. There was a shriek, and the grown-up let go and thrashed about like a wounded animal.

That might hold the others up. Sam crawled on. He risked another burst of light. The bottom of the train seemed to stretch away forever ahead of him, but off to one side was a dark hole in the tunnel wall. Maybe a way out?