It took forever to get her across. Bravely, she didn’t make a sound, though Sam could see that it was agony for her, with her infected lungs and her wasted legs. But she struggled on, and, with the Kid pulling and Sam pushing, she at last got through both windows and into the next car.

Sam jumped up after her and wriggled through without any trouble. He was so intent on helping Rhiannon that he barely noticed his own aches and pains.

As soon as Sam put his feet down, the Kid was off and moving.

This car, which Sam had caught glimpses of when Nick had let him go to the toilet, was used as a storeroom. All the pathetic bits and pieces that Nick and Rachel had collected from underground were in here. Chairs and tables with the tube logo on them, some tools, crates filled with bits of scrap metal and wood, coils of wire, piles of old newspapers and magazines.

The children hurried down the central aisle, half dragging Rhiannon, until they got to the doors at the far end, where there was more broken glass strewn on the floor. The Kid scraped it aside with his sneakers and once again laid the cardboard across the sharp edges of the window frames.

They repeated the same maneuver as before, but it was even harder this time. Rhiannon seemed weaker and more breathless. Sam remembered helping his mom put his duvet back in its cover after it had been washed, how the duvet was big and floppy and wouldn’t go where you wanted it to. It was the same with Rhiannon, trying to somehow shove her up and through the narrow gap.

Sam was sweating and tired out when they finally got her through, and she landed with a nasty thump on the other side. He quickly hopped up after her, though, and clambered across.

They settled Rhiannon on a seat, and she rested. Sam looked around. This car was where Nick and Rachel kept spare food. Cans mostly, filled with fruit, vegetables, meat, pudding, fruit juice, and soup. There was even a separate stack of dog and cat food.

“Where’d they get it all?” asked Sam.

“Some of the under-the-ground stations, they got shops in them, gyms, clubs, all sorts, you poke about down here, baby, you’d be amazed at what you turn up. Mark my words.”

“So much stuff,” said Sam. “Surely they don’t need any more. Maybe you were both wrong. Maybe they weren’t going to eat us.”

“They were looking through a telescope,” said the Kid. “Looking ahead. And they has a plan. Fatten you up on the stuff they don’t want to eat, then eat you when you’re ripe and juicy.”

“I feel sick,” said Rhiannon.