One

Jane ground the thought under his heel and upped his pace. He had developed a feel for distance and wanted to improve his daily mileage after his sickness had reduced him to a snail's meander. Becky didn't say a word but fell in step with him. The jolting of the wheelbarrow eventually wakened Aidan, but he didn't speak either. He watched Jane as if unsure of who he really was, or trying to assimilate him with the thin figure he had spotted on the bench, rattling in his sleep.

They stopped at a place where the M1 and the A1 split into separate roads. West of here was a town. Jane found some hiking boots for Aidan, who was wearing trainers that were beginning to unravel. It was difficult to shield him from the worst of the casualties but in the end Aidan just told him it was OK. Dead things didn't scare him. It was the living he was worried about.

Some of the dead bore unusually specific injuries, as if the heat had been focused on a plane. Jane thought about that a lot. It suggested something other than a random explosion or explosions. A woman whose clothes had been incinerated off her body had been burnt across her back, but there was an unaffected line of skin next to her spine, as if that scimitar of bone had shaded it from the fire. Other people were burnt only on their hands or faces. But it had not been this flash that had killed them; an ambient heat had cooked them from the inside out, like a microwave oven.

They found a supermarket but Jane told them to wait a while before entering; they sat on a wall and watched the door. The shelves were packed with bad food. Thousands of tins that had been compromised in some way: splits and pits and punctures.

'What happens when the food runs out?' Aidan asked.

'It's not going to run out,' Jane said. 'Think of all those millions of houses. All those millions of tins.'

'There isn't much here,' Becky said 'And a lot of the stuff we've found in the houses so far has been damaged. Exploded because whatever it was that hit us cooked everything inside the tins. Getting the shits from a dodgy meal isn't funny any more. It can kill you.'

'There's plenty. We just have to think.'

Aidan said, 'The shits.'

Jane led them along the aisles and checked underneath the bottom shelf. Only a tin of broad beans. 'See,' Jane said. 'Everyone else missed this one.'

'Or left it on purpose,' Aidan said. 'I don't like beans.'

Jane led them to a curtain of plastic at the back of the supermarket. It had melted from the doorway and resolidified into a weird polymeric puddle. They crackled across it and into the delivery bays beyond. An articulated lorry was parked outside. All of the pallets in the bays were empty. A fork-lift truck lay on its side, whatever it had been carrying incinerated. Jane unclasped the hitches on the canvas flanks of the artic and threw them back.

A smell, sweet and rank, hit him like a fist. He recoiled. Nothing good in there. He saw the soles of feet, maybe half a dozen people sitting up against the back of the lorry. Everything on the pallets already taken or spoiled. Back in the delivery bay there was nothing but a large lidded yellow skip, some cleaning fluid and mops. A radio that didn't work.

'We'll find something at the next one,' Becky said. 'And all those houses. There must be tons of food.' Her face clouded at this, though. Jane could see how appetites might be tested if they had to resort to wading through bodies to get to their cans of button mushrooms and new potatoes.

They were heading out but all Jane could think of was the skip. 'Wait for me here,' he said. 'I need to check something.'

'But Richard—' Becky protested.

'Please, let me do this,' he said. 'Think of it as training for the future.'

He thought that maybe she muttered something like 'What future?' but he didn't stop to argue the toss.

He went back to the delivery bay and pulled a shopping trolley over to the skip. He tipped the trolley over onto its side and stood on it. The lid of the skip was secured with a padlock. Vents showed him how things were thrown in. He stepped off the trolley and looked around him. He saw a sign in the neighbouring car park. He walked to the back of the delivery area and clambered over a bowed diamond-link fence. He crossed a wasteland of aggregate and glass and cindered chickweed. Another fence led into the garden area of a DIY megastore. Everything black and cowed. Great twenty-litre packs of obliterated compost. Hostas and acers and rhondodendrons in large earthenware pots. Bamboo like cross-hatchings in a grim cartoon. Plastic garden furniture bent and bubbled by heat. Concrete statues reaching to the heavens, blinded by soot. He touched one of the hosta leaves and it collapsed to dust.