Aidan’s parents are both dead, and he drifted out of touch with his stepfather a long time ago. He has a brother and a sister, seven and nine years older than him respectively, with whom he exchanges Christmas cards every year, though he speaks to neither of them. I found their details in his address book and rang both to ask if Aidan was with them. Both said no and sounded alarmed by the suggestion that he might be.

I am not disheartened. I knew I would find him in none of these places, with none of these people, and always expected that I would have to take the next step.

For the second time, I am about to set off to 15 Megson Crescent. I’m not scared any more, neither of Mary nor of finding Aidan there. It will be almost comforting to have my worst fears confirmed, as I know they will be. A conspiracy: the hardest thing of all to forgive; conspirators who don’t care if you forgive them because they don’t care about you and never did.

Because there’s only one way that any of this makes sense: if Aidan and Mary are working together to drive me out of my mind.

I lock the workshop. As I pull my car keys out of my pocket, a scrap of paper falls to the ground: Charlie Zailer’s mobile phone number. I asked her for it last night; she looked as if she was going to say no at first. I pick it up, feeling guilty for ignoring her advice: Don’t go to Mary’s house.

I drive along the Silsford road, under the overhanging trees that lean in on both sides to meet in the middle—a tunnel of lush foliage. Where I am now it’s beautiful, but soon the trees will thin out, the road surface will deteriorate, and I’ll see grimy squat houses that make my lodge house look enormous. A little further on I’ll pass the primary school that’s made of grey-green concrete and looks like a prison block, and Bob’s Bargain Centre on the corner of the street that leads to the Winstanley estate.

Last time, I drove so slowly I must have looked like a kerbcrawler—anything to put it off. Today I slam my foot down on the gas. I want to get it over with.

Her house hasn’t changed. Aidan’s car isn’t parked outside, or anywhere else on Megson Crescent. I bang on the door. ‘Open up!’