‘You loved her so much you made sure she was murdered,’ Ian said quietly. ‘An innocent girl died because of your capriciousness, and an innocent man’s reputation was destroyed. My dad lost everything – his job, his dignity. You didn’t just kill Becky, you ruined his life, too, and my mother’s, and mine! The truth is out at last, but the damage is already done.’

‘Ian, please.’ Sasha stepped closer to the three teenagers tied to chairs in front of him. ‘Let those kids free.’

But he ignored her. ‘And you killed Lydia too, I expect, because you knew she had betrayed you to me.’

‘No.’ Karin shook her head. ‘I never killed her, I would never do that.’

‘You’re a liar, just like Swann.’

Karin dropped to her knees, bowing her head. Tears spattered on to the flagstones. ‘I told you what happened, and I’m glad. Go ahead, I want the world to know. You’ve got what you wanted, so please let them go.’

‘Oh, no!’ he said in triumph. ‘The world needs to see what you’re capable of.’ He stepped in front of Karin, lifting the tip of the knife under her chin so that she was forced to look up at him. ‘I told you, you have a choice to make. Two of these children will walk out of here, but one of them must die with me, and you’re going to choose which one.’

Sasha maintained eye contact with Angel, who shook in terror, but she struggled to control her own spiralling panic.

Shaking her head in disbelief, Karin whispered, ‘I won’t do that.’

‘Who are you going to leave behind?’ Ian placed a hand on the shoulder of each teenager in turn, making them cry out in terror. ‘Michelle’s daughter… or your favourite pupil… or the policewoman’s kid?’

‘Why is Angel here?’ asked Sasha quickly. ‘What has she got to do with any of this?’

‘That’s a good question.’ He scratched his cheek with the blade. ‘When he could still talk, my father told me everything about what happened on the night of Becky Haskell’s death, DI Dawson, even his brief encounter with you. You were just an upstart probationary PC but you had the temerity to challenge his authority in front of his colleagues. Oh, he remembered you. Every single moment of that terrible night was burned on his brain.

‘So I knew perfectly well who you were when you visited him at the home, and it was such a delicious piece of symmetry that it was you who came. And when I saw you and Karin together, it gave me an idea. It didn’t take much to find out about your son and your husband.’ He cupped the back of Angel’s neck, making her go rigid with fear. ‘And, of course, your darling daughter.’