I swallow down nausea and then go back to Harper and check her pulse. Her eyes are closed, and her skin is pale and clammy. Her injuries are severe, but they’d probably be survivable in normal circumstances. But she’s still recovering from major heart surgery: given what her body has already been through in the past few weeks, I’m not sure she’s going to survive this. I pray to God I’m wrong. If it wasn’t for her bravery, neither Peter nor I would have survived in this cellar more than a couple of days at most. We owe her our lives.

‘Peter knew Felix was here,’ I tell Tom, keeping my voice low.

Tom’s jaw drops. Even in the dim light spilling from the hallway upstairs, I can see horror and shock in his eyes.

But not disbelief.

‘He knew?’ Tom echoes.

‘Since the beginning.’

Tom rubs his hand across his face. ‘Christ Almighty.’

‘Stacey was the adult here,’ I say. ‘Whatever Peter may or may not have known, he’s only ten. She probably terrified him half to death. What happened here is on her.’

Tom looks at me over Harper’s head. He doesn’t need to say anything. We both know what our son is. Stacey and Peter had a meeting of minds, a partnership of equals, regardless of the age difference between them. He was the one who made me see I couldn’t let Felix leave the cellar. Without her acolyte to egg her on, would she still have doomed her husband to his excruciating death? Who was the real master here, and who the disciple?

‘This is on Stacey,’ I insist. ‘She tried to kill our son. She put him in the freezer.’

‘She put him in the freezer,’ Tom echoes.

I wonder if the words sound as hollow in my mouth as they do in his.

This isn’t just on Stacey, and we both know it. For all her monstrous behaviour, Stacey wasn’t entirely irredeemable. She felt some compunction about what she did; maybe even regret. Her relationship with Felix was far more complicated than we’ll ever know: I think she loved and hated him in equal measure. And she wanted me to be with my son when he died: however warped her thinking, she was trying to do right by me. She gave me the Stanley knife, either to give me an easy way out or a fighting chance: I honestly think she meant it when she said she liked me. And she certainly admired my son. Was actually fond of him, in her own way.

I don’t think Peter is fond of anyone.

I think my son is incapable of empathy. I think he could kill a man as easily as swatting an ant, without doubt or hesitation.