‘This way,’ he said, hurrying over the road towards the arch. They cut across the roundabout, heading for the north-west corner. They were all breathing heavily, their hearts pounding against their ribs. It had been hard enough on their nerves just trying to get away from David, but at least with him the worst they had to fear was an argument and maybe a scrap.

Out here it was different. The darkening sky, splashed red in the west, made them all fearful. It took them back to caveman days when humans must have been terrified of what lurked in the dark. Now, when the sun went down, every kid in London had learnt not to go out on the streets, learnt to be scared again.

For a start there were no streetlights. The dark really was the dark, in a way it hadn’t been in London since the blackouts of the Second World War. The main thing, though, was that the sickos came out at night. On the whole they shunned the sunlight. Bolder ones, healthier ones like the gym bunnies, braved it, but most of them, the least human, the most diseased, stayed hidden until it was safe for them to crawl out of their hiding-places and roam the streets looking for food.

Any kids who hadn’t found somewhere safe for the night were prey. Over the last year most kids had joined together into larger groups and found their way into easily fortified camps like the palace, or the Tower, but there were still smaller groups living scattered in the houses, preferring to look after themselves. And they were more vulnerable.

No one knew how many sickos were still alive. But you could hear them at night, gangs of them on the prowl. Even in the daylight you had to be careful that you didn’t disturb a nest of them. They were everywhere – in cellars, in the underground tube tunnels, in the sewers, anywhere dark. They didn’t need light. They hunted by smell. DogNut knew that he and his friends would have to keep moving or risk attracting the bolder sickos who would be emerging from their lairs now that the sun was disappearing.

‘Keep to the middle of the road!’ he called out as they jogged along. ‘And stick together.’

They headed west, towards Knightsbridge and the blood-red sky that hung above it. This had been one of the most expensive areas of London, with tall old buildings and expensive shops. Now all derelict.

They passed a super-modern Jaguar car showroom. The building that rose above it looked like a Lego building, all pointy roofs and tall chimneys and fancy walls made of rows of red and cream bricks. Other buildings had turrets and towers, or pillars across the front. Now and then they passed a new one, all glass and steel.

God, thought Courtney, London just went on forever, so many houses, offices, shops, banks, restaurants, so many people. What had happened to them all?

As if in answer to her question, she heard a howl and the kids staggered to a halt, looking around uncertainly, trying to see where the sound had come from. Courtney edged closer to DogNut, gripping her spear tighter.

‘We need to keep moving,’ said DogNut. ‘It’s getting darker every second.’

‘Maybe we should go back,’ said little Olivia.

‘No way,’ said DogNut. ‘We carry on. We always knew it wouldn’t be easy. We can’t go running back to Mummy every time we hear a noise.’

‘I’m scared,’ said Olivia. ‘Let’s please go back. I liked it at the palace.’

‘You want to find your brother, Paul, though, don’t you, love?’ said DogNut, and Olivia nodded tightly. ‘Then we need to push on.’

‘Besides, that sound could have come from anywhere,’ said Courtney, trying to be helpful. ‘It could have come from behind us.’

She instantly knew it had been a mistake to say anything because Olivia grew even more fearful. She started to shake and sob. Courtney didn’t want her to freeze and put them all in danger. She grabbed her hand.

‘It’s all right. We’ll be all right. It’s not far.’

Olivia nodded again, biting back tears.

They carried on. Moving slower than before, not wanting to rush into danger, listening, looking, smelling the air for the telltale sour, rotten odour of sickos. There was so much filth on the streets, though, it was hard to pick out any one particular smell.

They heard another howl. It sounded more distant than before.

‘See,’ said Courtney, squeezing Olivia’s hand. ‘It’s going away, whatever it was.’

‘Was it a sicko?’

‘Could have been a cat or fox or anything.’

‘I wish we’d waited until the morning.’

‘We’ll be all right. We’ll find your brother, OK?’

Olivia’s eyes went wide. ‘What if he’s dead?’

Courtney sighed. ‘Can’t you think of something nice? Don’t think of bad things all the time.’

‘I can’t help it.’

Courtney was beginning to regret holding on to Olivia’s hand. She was stuck with her now and the little girl was being a real downer. All she was doing was making her more scared and depressed. Everyone probably felt the same way as Olivia, and it really didn’t help spelling it out. She was about to say something to the little girl when there was a crash from the side-street they were passing.

‘What was that?’

‘Probably nothing.’

It wasn’t nothing, though – it was three sickos, who, a moment later, stumbled into the road, carrying an unidentifiable dead thing. They were all three mothers; two of them very tall and skinny, the third much older, bent over, bald, her belly hanging down to her knees. The sickos were as surprised to see the kids as the kids were to see them. They stopped, eyes goggling.

‘Run!’ wailed Olivia.

‘No,’ said DogNut firmly. ‘We ain’t running. If they want an argument, we’ll give them one.’

As he said it, he tugged his sword from its scabbard, and Felix and Marco formed up on either side of him, weapons at the ready. Courtney let go of Olivia and joined them, trying to appear braver than she felt. Finn took charge of the little girl and kept behind the others, cursing his useless, swollen arm in its sling. The slightest touch sent daggers of hot pain all the way up to his shoulder. In the last couple of days it had become a lot worse. He couldn’t hold anything – in fact, could hardly move the arm at all, and his fingers had become fat and puffy. He also felt slightly feverish, which frightened him.

Stupid thing was, it hadn’t even happened in a battle – he’d slipped on some wet steps at the Tower and gashed himself on a piece of jagged stone.

‘Come on then,’ said DogNut, waving his sword at the mothers. ‘You want some? Come and get it then. What are you waiting for?’

The older mother drew her blistered lips back, exposing toothless gums, and hissed at the kids, then waddled forward, her companions joining her in a clumsy charge.

‘Don’t look, Olivia,’ Finn said kindly, covering the girl’s eyes. ‘Turn away.’

The fight lasted less than a minute. The kids laid into the adults with a ferociousness born out of stress and tension. The three sickos went down fast and stayed down, bleeding into the gutter.

The kids cleaned their weapons and carried on, almost hysterical from their victory and the sudden flood of relief. They were laughing as they walked, talking over each other in a mad, excited jumble as they recalled the events of the fight.

‘Did you see the look on the old bat’s face when I twatted her on the side of the head …?’

‘I thought my spear was gonna get stuck! I forgot to twist it …’

‘You got to be well careful with a sword and all, better to slash with it than to stick the point in …’

‘How did they ever think they could win?’

‘They ain’t had to deal with kids like us before. Only the wimps from round here. We’re Jordan Hordern’s soldiers; we’re trained, we’re the elite …’

‘We’re kings of the streets!’

‘Hey, look at that,’ said Courtney, and they all stopped walking.

They had come to a fancy pinkish-brown building with a big dome on the top. Tatty flags hung along the front above a row of ragged green awnings.