This rooftop landing zone was the highest point around. Max had never been to London before, but he identified the River Thames glittering in the sunlight. In the few seconds he had to look around, he saw landmarks he recognised from TV – the Houses of Parliament. St Paul’s Cathedral. The Shard. Up here, there was no sense of movement down below, of anyone hurrying. He knew it was just a trick of the height. They were truly in the heart of the city.

The sky was clear but the wind was high. It wasn’t simply the downdraught from the Chinook. The top of this building was buffeted from all sides. Max felt unsteady. He heard someone shout, ‘Get off the landing zone!’ Wind howled in his ears as he followed the instruction. He ran after Woody and Angel, who were carrying their flight case to the top of a stairwell at one edge of the building. The others followed. They descended several stone steps and went through a heavy metal door into the top floor of the building. Two military men were waiting for them at an open lift. Max, Woody, Angel and the other recruits crowded in. A minute later Hector joined them. There was no sign of Ash and nobody asked where he was. Max thought he could hear Green Thunder taking off, however. He figured Ash was still inside.

The lift took them to the ground floor in tense silence. The doors slid open on a large reception area that had evidently been cleared of any members of the public. There were glass windows on all sides, but they were blocked on the outside by six-foot-high screens. Beyond them, Max could see the blue neon flash of police lights. There was a distant sound of sirens.

Four people were waiting for them – three men and a woman. The woman took Abby and Angel to one side, out of sight. The men started to hand out casual clothes to the remaining boys.

‘Get out of your camouflage gear,’ one of them shouted. ‘But don’t start getting into these clothes yet.’

Max gave the others a sidelong glance. They were hesitating, clearly a little embarrassed about stripping. Max shrugged and removed his boots, jacket, T-shirt and trousers. By the time he stood in his socks and boxer shorts, the others had followed his lead. One of the three men approached him with a handful of wires and a roll of black duct tape. He handed Max a small box, no bigger or thicker than a fifty-pence piece. A black wire led from it. ‘Tape this to the inside of your thigh, beneath your underwear,’ the man said in a gruff, no-nonsense voice.

‘What is it?’ Max said.

‘Communications wire and microphone. Highly advanced tech. Only available for high-level military operations. It’ll allow us to hear what’s going on in your vicinity.’