‘We’ve got time,’ he said.

‘Are you mad?’ said Kirsty.

‘Are you going to come or not?’ said Johnny.

‘Where?’

Johnny took her hand, and reached out for Yo-less with his other hand.

Then he nodded towards Tom, who was still staring at the flames.

‘Grab him, too,’ he said. ‘We’ll need him when we get there.’

‘Where? ’

Johnny tried to grin.

‘Trust me,’ he said. ‘Someone has to.’

He started to walk. Tom was dragged along with them like a sleepwalker.

‘Faster,’ said Johnny. ‘Or we’ll never get there.’

‘Look, the bombs have fallen,’ said Kirsty, wearily. ‘It’s happened.’

‘Right. It had to,’ said Johnny. ‘Otherwise we couldn’t get there before it did. Faster. Run.’

He pushed forward, dragging them after him.

‘I suppose we might be able to … help,’ panted Yo-less. ‘I know … first aid.’

‘First aid? ’ said Kirsty. ‘You saw the explosions!’

Beside her, the young man suddenly seemed to wake up. He stared at the fire in the town and lurched forward. And then they were all running, all trying to keep up, all causing the others to go faster.

And there was the road, in that direction.

Johnny took it.

The dark landscape lit up in shades of grey, like a very old film. The sky went from black to an inky purple. And everything around them looked cold, like crystal; all the leaves and bushes glittering as if they were covered in frost.

He couldn’t feel cold. He couldn’t feel anything.

Johnny ran. The road under his feet was sticky, as though he was trying to sprint in treacle.

And the air filled with the noise he’d last heard from the bags, a great whispering rush of sound, like a million radio stations slightly out of tune.

Beside him Yo-less tried to say something, but no words came out. He pointed with his free hand, instead.

Blackbury lay ahead of them. It wasn’t the town he knew in 1996, and it wasn’t the one from 1941 either. It glowed.

Johnny had never seen the Northern Lights. He’d read about them, though. The book said that on very cold nights sometimes the lights would come marching down from the North Pole, hanging in the sky like curtains of frozen blue fire.

That was how the town looked. It gleamed, as cold as starlight on a winter night.

He risked a glance behind.

There, the sky was red, a deep crimson that brightened to a ruby glow at its centre.

And he knew that if he stopped running it would all end. The road would be a road again, the sky would be the sky … but if he just kept going in this direction …

He forced his legs to move onward, pedalling in slow motion through the thick, cold, silent air. The town got closer, brighter.

Now the others were pulling on his arms. Kirsty was trying to shout too, but there was no sound here except the roar of all the tiny noises.