I can only say it in my head, not out loud. I can tell the story to myself. Mary’s painting might have been a way to get revenge on Aidan at first, to prove she could beat him at his own game, but it came to mean more to her than that. She was good at it—not just good; brilliant. It gave her something she recognised, even in her misery, as being valuable. After a while—maybe months, maybe years—cutting up painting after painting of Aidan and adding it to the pile wasn’t enough for her. She could see she was getting better. Painting wasn’t Aidan’s talent any more, it was hers. She stopped feeling as if she was attacking Aidan when she carved a canvas to pieces with a knife, or hacked at it with a pair of scissors; she was attacking herself, her own work. She didn’t want to do that any more. Something had to change.

She started to paint other pictures that weren’t of Aidan, ones she kept. The ones I saw in her house, of the family who used to live on her estate, and the Abberton series. Those might not have been of Aidan, but they were about him. About what she did to him. They mattered to her. They were the story of her life.

‘You . . . got scared.’ I stop, try to fill my lungs with the air I need to carry on. ‘You understood . . .’ I want to tell her I know how she felt.

‘What? What did I understand?’ She shakes me, and I let out a howl of pain. My body throws out a last spurt of energy to fight it. I use it to get more words out. ‘You understood . . . how it would feel to have your pictures . . . destroyed. The worst thing . . . what you’d done to Aidan. You felt guilty.’ That’s why you won’t admit it. The guilt, once you felt the full horror of what you’d done, was more than you could bear.

‘I don’t believe in guilt,’ says Mary quickly. ‘My therapist said it was an unproductive emotion.’

I see how it must have happened: her guilt and shame transmuted into paranoia, that Aidan would find out about her—where she was living, what she was doing. That he’d do to her what she’d done to him. She couldn’t risk it. The only way to make sure it never happened was never to sell any of her paintings, to maintain absolute control. She was terrified of what Aidan might do to her, of the punishment she felt, deep down, that she deserved from him. At the same time, she couldn’t resist the impulse to close in on him, once she knew where he was—to infiltrate his life, lurk on the edges of it, where he might just notice her.