Knowles had already taken a knee as Meyer fell, ready to collect the beaten man’s pistol. It gave Dupart and Cunningham no time to react. No time to rush forward. No time to retreat.

Knowles rose back to his feet. Slowly. His pistol trained on Dupart.

As he stood up, all four doors to the Oval Office burst open. Secret Service agents streamed in. Reacting to the gunshot they had heard moments before.

Knowles eyed the group as they entered, and stopped them with the same raised hand motion Dupart had used. He felt every set of eyes burning into him. Men and women sworn to protect him; this was not the scenario they had expected.

The president with a gun, Knowles thought. Now who do they protect?

He turned his attention back to Dupart.

‘Am I the first one to do this, Nick?’

Dupart’s eyes were fixed on the gun.

‘Still think you own this office?’

‘Killing me changes nothing.’ Dupart stumbled over the words. His demeanour had changed in an instant. He was desperate. ‘Someone will take my place.’

‘You know, I don’t think that’s true,’ Knowles replied. ‘Not with everything you just said. And if it is, well, I think I’ll cross that bridge when I come to it.’

He had made up his mind and he did not hesitate, leaving less than a heartbeat between his final word and his first bullet.

Three more and he was done.

Every Secret Service agent in the room stood rooted to the spot, unsure how to react, as Knowles stepped forward and looked down. At Dupart. At Cunningham. Both lifeless at his feet.

‘Because no one owns the White House.’

EIGHTY-ONE

Nizar Mansour looked up from his bed as two men entered the Belmarsh intensive care suite. It was one of the few private spaces in the prison’s hospital wing, designed for only one patient at a time. For the past five days, that patient had been Mansour.

He recognised the men on sight. Detective Chief Inspector Bruce Bull and Will Duffy.

For almost all of his five days in the suite, Mansour had been in an induced coma; the preferred treatment for the swelling his brain had suffered after his attack. The first two of those had included around-the-clock police protection. In case he was targeted again.

That threat had subsided three days ago following events in the United States and in Afghanistan, the details of which Mansour would never know. And so for those three further days he had been in here alone.

He had finally been brought out of unconsciousness that morning. Four hours later, Bull and Duffy were his first visitors.

Duffy approached the right-hand side of the bed, while Bull took the left.

‘How you feeling, lad?’

‘I am much better, I think,’ Mansour replied. ‘I . . . I . . .’

Bull stepped in.

‘You don’t need to speak, Nizar. You’re still recovering.’

Mansour smiled a thank you. His head was a strange mixture of pain and fog, and finding the correct words was difficult.