It’s pitch black in here: absolute darkness, crow black, blacker than night. It’s impossible to know how long we’ve been down here, or whether it’s day or night outside in the real world, which already seems as hazy as a distant dream, a vacation taken long ago.

The protective effect of the adrenaline has worn off and the pain in my butchered hand is agonising. I can’t seem to quite stop the bleeding, either, though the tourniquet has slowed it. The cold from the concrete basement floor is seeping into my bones. I just want to sleep, but if I do that, there’s a real risk I might not wake up, and if I die, my son dies with me. So I drag us both across the floor to the cellar wall and force myself to sit upright, cradling Peter in my arms, reciting the periodic table and the bones of the human body and the steps of a coronary bypass aloud in an attempt to keep myself awake.

‘Mummy?’

His voice in the darkness jolts me. ‘Peter! You’re awake!’

‘I’m cold,’ he says.

‘I know you are, sweetheart,’ I say, unable to keep the relief from my voice as I tighten my embrace and try to infuse what bodily warmth I have left into his limbs. If he’s cold, he’s awake. If he’s cold, he’s going to live. ‘I’m right here, Peter. Try to move your legs if you can.’

He doesn’t respond. He doesn’t ask any questions. I don’t know if his torpor is physical or psychological, but I need to get him moving. I need him to fight.

‘Come on,’ I say. ‘Up we get. Come on, Peter,’ I urge, as he slumps, inert, in my arms. ‘We have to get up. We have to move and stay warm.’

Fireworks explode behind my eyes as I force the two of us to our feet, the pain in my hand so intense I have to steady myself against the wall. Peter whimpers as the blood starts to circulate in his legs, piercing him with pins and needles, but I refuse to let him rest. We stumble across the cellar in the dark, and when we reach the opposite wall, I turn him around and propel the two of us back. I’m grateful for the darkness so he doesn’t have to see Felix’s bloody corpse on the bed.

I don’t know what he knew about Felix and when, but he’s not responsible for the man’s death. That’s on Stacey. Whatever she tells herself now, she never intended her husband to walk out of this cellar alive. Dragging my son into it was just a sideshow to the main event. A bonus. She saw the darkness in him and she took pleasure in drawing it out and setting it free.