‘Sometimes, when we’re afraid, or thinking something bad is going on, our brains can do weird things. Like trick us into seeing and hearing things that aren’t really there.’

He takes a deep breath in and holds it for a while before letting it huff out again. ‘I see what you mean, but I don’t know if I believe it. I don’t mean I don’t believe you. But I know how I feel, and I know what I’ve seen. I don’t think it’s a dream or my brain playing tricks, Mum.’

‘Okay. Then I think we might have to do a bit of detective work. How do you feel about that?’

Finley sits up tall, smiling. ‘Cool. A detective, like Dad! Shall we set a trap?’ he says, excitedly.

‘I think so.’ I hope I don’t regret this. I suddenly feel like a completely irresponsible parent dragging my eight-year-old son into this. ‘What do you propose?’

‘I say we go full-on Home Alone!’

‘Oh, erm … I think that might be a bit much, Finley. I don’t want to frighten your brother. I was thinking a little more undercover – like setting up a camera.’

‘Aw, Mum. That’s a bit boring.’

‘Ask your dad – it’s what the police would do.’ I smile and hope Finley buys it.

‘Fine. We can do that for starters, I guess.’

‘Good. Right, let’s get started.’ Guilt pulls at my conscience. Am I drawing my son into my delusional thinking? What will Nick think if he hears about this? ‘Fin, love?’ I say.

‘Yeah?’ He’s already up and walking towards his room. I follow.

‘Can we keep this to ourselves for a bit?’ I whisper. I don’t want to wake Leo.

‘You mean keep this as our secret?’

‘Well, not a secret, as such. You shouldn’t agree to keep secrets, really, Finley.’

‘Really? Why not?’

‘Because sometimes people who ask you to do that are doing it because what they’re doing is wrong …’ I feel I’ve opened a whole can of worms with this. But I don’t want Finley being encouraged to think it’s okay to keep secrets because, ultimately, that could be a harmful thing for him to learn.

‘So, what are you asking me to do then?’

‘I don’t want to alert your brother to what we’re doing because I think he’ll worry. As soon as we have some evidence something is going on, we’ll go straight to Daddy with it. So, not a secret – but a work-in-progress that only you and I are involved with at the moment.’

‘Sure. I get it. Don’t worry, Mum. I’m more grown-up than you think. I am almost nine.’

I touch my fingertips to his baby-soft cheek. I want to cry. ‘You’re a good boy, Finley Miller. I’m sorry this is happening.’