‘You heard him before,’ Celia replies. ‘He said he’d see her tomorrow. Anyway, the man is so emotionally retarded he’s probably gone back to the bar to get drunk.’

‘But what if he does come back?’ Malcolm presses.

‘Then we’d better hurry up and get this done,’ Celia snaps. ‘We have to do this quickly anyway; the blocker only works for around six minutes and I really don’t want to have to give her another dose.’ She turns back to me. ‘Toby and the others think Malcolm and I have gone to our room for the evening. While I came here to keep an eye on you, Malcolm waited in for room service and rented a movie on demand, so everyone will think we’re spending the evening in our room. Which is where we’ll be heading right after we’ve finished up here.’

‘There we go.’ Malcolm sounds pleased with himself. ‘I think that’s the right height.’

Celia looks up. ‘I think you need to make it a bit longer. Zoe’s shorter than you. Otherwise it’s going to be tricky to get her up there.’ She scratches the side of her mouth with a gloved forefinger.

‘Hm, I think you’re right,’ he replies. ‘Maybe another couple of inches.’

Although my body is paralysed and my vocal chords are silent, inside I’m screaming. How can they discuss this so calmly, as though they’re talking about some innocuous DIY project? Neither of them seems remotely distressed by the fact they’re about to commit a murder. My murder.

Celia bends down a little to look me in the eye. She wipes some of the drool from my chin with the finger of her glove. ‘There was no need for Toby and Nick to know what we’re doing here. I’m not certain they’d approve. Toby does still love you and he’ll be quite upset that you decided to end things. But I’m sure you must realise that, as a parent, you’ll do anything to protect your children.’

‘Okay,’ Malcolm says. ‘I think that should do it.’

Celia gazes up at the ceiling critically. ‘Yes. Good.’ Malcolm huffs his way down off the chair as his wife resumes talking to me. I don’t know why she’s bothering. She’s about to kill me, so why take the time to explain all this? Maybe she finds it cathartic. Or maybe she’s proud of her plan and wants to show it off. Or perhaps she’s simply a sadistic bitch who wants to terrify me.