One

He took the skull out and inspected the great circles of its orbits. He blinked and something in the light allowed him to see the fierce, fixing yellow glare of what had once turned within those sockets. The focus, the deadly intent. It chilled him that something so small could be so violent. It had been built for the purpose of death. It had nothing in it other than the instincts of procreation and killing. He felt something stir inside him and suppressed laughter. He'd felt a sudden bond with the creature, with that way of life. He supposed it was in all people, that flicker of race memory, the hunter-gatherer mentality. The so-called civilised lifestyle had rubbed its edges away over the centuries. But it was still there, the romance of it, the grizzly part of you that got a thrill when you picked up a fishing rod or headed into the forest with a sleeping bag rolled up on your shoulders.

He put the skull back in his pocket and hitched his pack tighter around his shoulders. He gave one last troubled look at the sky and hurried after the others. There was a marked disintegration in their mood when he caught them up. They had stopped snapping and talking over each other. Now there was a grim silence and a distance between them. Chris seemed crestfallen; Jane wondered if Nance had finished their relationship. He felt like laughing. You survived the end of the world, fate dumping you, and you get all mopy because your girlfriend tells you to lump it.

It was Nance who drew his attention, however. She was still sweating, still doing that weird flex of her hands, as if she was suffering from a muscle spasm or a trapped nerve. Chris noticed it too, but although he kept shooting her looks he didn't say anything.

'We'll hit the road soon, then we can pick up some speed,' Jane said. 'I've been making good time. It's all about rhythm. And making sure the weight of what you're carrying is well distributed.'

They didn't appear to hear him. He put his head down and concentrated on walking.

They'd covered around five miles through the dusty expanses of meadows and fields and forestland, all of it layered with ash and limbs of charcoal, the heat causing them to gasp and swear; Jane could feel the burn through the soles of his boots. This land would be a long time cooling down. The road was not worth considering. It had bulged and buckled; it looked as if some giant hand had gripped it further along and yanked it like a strip of carpet. Crash barriers and fallen street lamps created further obstacles. It was tough going on the farmland, but at least it was level and consistent. Up ahead electrical pylons had crashed to the ground. Hopefully the road would be fit for walking before they had to navigate those. He didn't want his discovery that the country's electricity had died to be a bad mistake.

They were coming to another stunted reach of incinerated wood when Nance shrugged her rucksack off and started running for the road.

'Hey,' Jane called.

Chris was already trotting after her. 'We won't catch her. She ran for her school. She had state trials.'

'Great,' Jane spat. They both lumbered in her wake. It must have been a good three miles to the dual carriageway and she just kept diminishing into the distance. Jane saw, before she skipped like a goat across the burst lava mass of blacktop, that she was wearing running shoes.

Five minutes later they were at the road too. Jane took his backpack off and rested it against the warped ribbon of a crash barrier, colour side towards the sea so that he'd spot it against the grey when he returned. Both of them were breathing hard. Jane thought the years of slog on the seabed, fighting currents, might have improved his fitness, but he guessed his lungs must have been damaged to some degree.

They tripped and skidded across the tarmac and followed Nance along a B road past a battered grain merchant's. Its grounds were host to dozens of silos, all of which had been lopped like boiled eggs. Tons of grain had been swept by the wind into drifts against brick walls and the burnt black skeletons of lorries. Beyond that and the railway, the earth sloped towards the sea.

'Where the hell is she going?' Jane cried.

Chris didn't answer but Jane received a reply when they started to run past items of her clothing. Chris gathered them up in his arms. He was calling out to her, but she would not stop. By the time they reached the coast, a further three miles away, Jane thought maybe his heart would burst. His clothes squirmed against his body, a layer of sweat sandwiched between them.

They staggered across a bluff of volcanic rock and onto the beach proper. An immense flash of heat had turned it into opaque leaves of obsidian: black, dark green, firebrick red. Their boots chinked and clinked. The sea was a horrendous churning stew. Bodies rolled upon the surf. Far away to the horizon, when the waves allowed them to see, they could see huge tankers upended.