When Knox reached the top floor of Kemp House he poured himself a large gin from the drinks trolley he kept permanently stocked in his living room and looked out over a different set of roofs.

As he watched afternoon fade into evening across the city he wondered what was wrong with him. He’d yearned to come back to London when he’d been away, but now he was home he felt almost nothing. Maybe he was just shattered from his travels, but the flatness seemed more pervasive, and more alluring, than just simple exhaustion. He needed to do something before it swallowed him, and turned this cold warrior completely numb.

He used to look down on the city like a king watching over his ancient domain. Now, every time he came back to Kemp House he’d discover his view had changed. Old buildings would have vanished and new ones risen in their place. Kemp House wasn’t even the tallest structure in the heart of the city any more. The slim, teetering column of Post Office Tower, with its cluster of aerials reaching up into the sky above Fitzrovia, had taken that crown, while, closer to Knox, the tessellated oblong of Centre Point was climbing higher and higher above Tottenham Court Road tube station. And the streets were different too: on the corners at the bottom of all these buildings the old Teddy boys had turned into mods, rockers, and hippies.

It felt like the city was evolving, and leaving him behind.

He thought about what Holland would say. He’d tell Knox to pull himself together and get on with his job. But he knew he wasn’t going to whet his edges by checking Laing’s dots and crosses. He needed a real reason. He just had no idea where or how to find one. Then he heard another voice. An American voice that belonged to an old friend. It was Abey Bennett’s, and it was telling him to pull his head out of his ass.

The phrase lodged in his mind, and stayed there. In fact, Bennett’s Midwestern accent only started to fade as he walked back into the R&D department in Leconfield House the following morning and found it completely transformed.

‘You better bloody well be here to help,’ White shouted at Knox over the sea of lab coats and uniforms that were crammed between desks and computer towers.

‘Whatever I can do,’ Knox shouted back as he fought his way over to White’s desk.

Knox had decided he’d dismissed their brief conversation the previous afternoon about the Russian submarine too quickly. And judging from the hive of activity he’d just walked into, he was right.

‘What’s happening?’ he asked when he finally reached White.

‘A breakthrough, I hope,’ he replied.