Fleet dived, catching Richardson around the midriff just in time. Richardson had one hand around Zack’s throat, driving him backwards across the wall. But Richardson’s tie bound them together, and the closer Zack came to tipping over the edge, the further Richardson was forced to lean, too. Fleet had his feet braced against the wall, and it was taking all of his strength to keep both men from falling.

‘Pull him up!’ he yelled. ‘For Christ’s sake, Richardson!’

But Richardson paid no notice. Every sinew in his neck was straining against the loop of silk that was tugging him forwards.

Suddenly he let go of Zack’s throat, and focused on the knife instead. But he was no longer trying to wrench it from Zack’s grip. Instead he was drawing it across his body.

‘No!’ Fleet roared, but he was powerless to intervene. If he let go of Richardson, both men would die.

With two hands now to Zack’s one, Richardson forced the knife closer to his own throat. Zack’s eyes narrowed in confusion – and then widened as he realised what was happening. He tried to fight it, but like Fleet there was nothing he could do. The knife was moving in slow motion, but when the blade touched the edge of the outstretched tie, the material was severed in a blink.

And then it was over. Fleet and Richardson were toppling backwards, and Zack was screaming as he plummeted towards the ground.

Sunday 27 October, 12.14 p.m.

‘Nicky? Nicky. Where is she? Is she—’

‘Rob, don’t.’ Randy was at the doorway trying to hold him back. There were other police officers on the scene as well, and the entire building had already been cordoned off. When Fleet and Bevan had seen the photograph of Zack on the DC’s phone, Bevan had immediately called it in, directing a team of officers to Shining Light. But they’d been too late. It was obvious they’d been too late. If Nicky were still alive, she would already be in the ambulance at the front of the building. And the fact that Randy was here at all told Fleet everything he needed to know.

‘I want to see her, Randy!’ He struggled to break Randy’s hold on his arm.

‘Rob. Rob. Just wait a minute, will you?’

Fleet was trying to get through the main door into the building, and for a moment he stopped struggling. ‘Wait for what? Is she in there? Why haven’t they brought her out yet?’

‘That’s what I’ve been trying to tell you. You’re going the wrong way.’

Randy pulled him towards the alleyway at the side of the building.