Whether it was by design or accident, Chris Petty failed to terminate the telephone call from the embassy before setting off in pursuit of his colleagues. He saw them almost immediately after making the turn at the Old Police House. They had covered about half the distance to the Reformers’ Tree and were approaching a pair of forest green Ford Transit vans parked along the edge of the path. It was not unusual to see workmen in the park early in the morning—Hyde Park was 350 acres in size and required near-constant care and maintenance—but their true purpose was revealed a few seconds later when the rear cargo doors swung open and eight well-armed men in black jumpsuits and balaclava hoods poured out. Petty’s futile warning shouts were heard and recorded inside the RSO ops center, as was the sound of gunfire and screaming that followed. Petty was hit ten seconds after the initial burst and his death agonies were captured on the center’s digital recorders. He managed to say only one word before succumbing to his wounds, though it would be several minutes before his stricken colleagues inside the embassy understood its meaning. Gardeners…

Gabriel heard the first shots while he was still in the open ground at the northern edge of the park. He drew his Beretta as he sprinted into the trees, then stopped on the footpath and looked in the direction of the Reformers’ Tree. Fifty yards away was a scene from his nightmares: bodies on the ground, men in black jumpsuits pulling a struggling woman toward the back of a waiting van. He raised the gun but stopped himself. Was this truly the attack or had he stumbled into a police drill or the set of an action film? Were the men in black really terrorists or were they police officers or actors? The closest body lay thirty yards away. On the ground next to the man were a mobile phone and a SIG-Sauer P226 9mm pistol. Gabriel crept quickly to the fallen man’s side and knelt beside him. The blood and bullet wounds were real, as was the look of death in the man’s frozen eyes. He knew then that this was not a drill or a film set. It was the attack he had feared, and it was unfolding before his eyes.