His stomach rumbled, and he froze. Had they heard it? It had sounded like a bear growling. He was so hungry. When had he last eaten? How long ago had it been? No idea. He had a bottle of water in his backpack, but he’d finished off the stale biscuits and tinned fruit he’d brought from Waitrose while he was hiding in the shaft.

Now wasn’t the time to be thinking about food. If he wasn’t careful he’d wind up as somebody else’s breakfast.

On he went. It must have taken him fifteen minutes of patient crawling to get to the end of the platform, but he made it safely and scurried into the comforting darkness of the next tunnel. He glanced back. The grown-ups were sitting exactly where they had been before. Not one of them had moved. Maybe they were already dead? He didn’t want to find out.

He turned and pressed on toward the next station.

As he walked, the water on the tracks grew deeper and deeper. At one point it was up to his waist. It wasn’t warm and it wasn’t cold, but it was still unpleasant. Black as oil with scum floating on the surface. He held his hands and arms up above it, keeping his precious flashlight well clear. Without light he would be lost and might end up wandering around down here forever.

No. Not forever. Only until he starved to death. His stomach gurgled even more loudly. There were sharp pains in his guts. He had to keep moving, and somehow he had to find something to eat.

The journey to the next station was a repeat of his journey from Camden to Euston, except that at one point he came to a junction with two tunnels leading off it. He chose one at random and kept going, trusting to blind luck.

After a little way, however, he found the tunnel was blocked by a big pile of what he at first thought was sticks. As he passed his flashlight beam over it, he realized that it was bones. Human bones, some still wrapped in clothing. Not bleached and white like skeletons in films, but a dirty yellowish gray. There were hands and legs and arms and ribs and skulls, all jumbled up on top of each other, stretching away down the tunnel. Maybe someone had piled dead bodies down here out of the way, or maybe the grown-ups had crawled down here to die. Whatever the reason, he could go no farther in this direction, so he backtracked and went down the other tunnel.

He’d sometimes wondered where all the dead grown-ups had gone. At first the streets of London had stunk. A horrible rotting smell that made you cover your mouth and nose with your shirt; but slowly it had faded away.

He shuddered. What other secrets were buried down here in the tunnels?