‘Don’t do that,’ says Waterhouse. ‘How can you do that to yourself?’

‘Easy. I don’t paint with my left hand.’

When I told you Saul had given me Mary’s address, the look on your face . . . you hadn’t realised until then that she was living in your old house, where you killed the real Mary Trelease. You must have been able to see that I was telling the truth, that the address meant nothing to me, but it’s hard to banish doubt once it’s crept in. You didn’t believe my love for you was unconditional, not after the way I’d reacted to your confession. And Mary—Martha—knew what you’d done. You knew that eventually she’d use that knowledge, use the power she had over you.

‘Hold on for the ambulance, Ruth. It should be here any minute.’ Waterhouse is talking to me. All I want is to know if Aidan’s alive or not. Why won’t he tell me that?

‘You’re not as clever as you think you are,’ I hear Mary say.

‘How clever is that?’

‘I followed you to London. You were following Aidan. You didn’t see me, did you? You took me straight to Gemma Crowther’s flat.’

‘You killed her,’ says Waterhouse.

‘Not me. Aidan.’ She knows I’m too weak to contradict her. She’s enjoying it: lying in front of me, knowing I can’t stop her.

‘You’re holding the hammer you used to knock her teeth out and hammer nails into her gums,’ says Waterhouse.

‘Aidan did those things. Why would I kill her? He wanted revenge for what she did to Ruth. Anyone would.’

‘If he was the one holding the gun on Monday night, how come he ended up getting shot?’ There’s a pause. ‘You’ve got no answer for that, have you?’

‘I’m not saying I didn’t shoot him. I’m saying I didn’t shoot Gemma.’ He’s made her angry. ‘You’re no Sherlock Holmes, are you? It’s okay, you don’t need to be. I can tell you what happened. ’

‘Go on.’

‘Where do you want me to start? Aidan had to find out about Gemma and Stephen for himself. Ruth told him nothing—can you believe that? No communication whatsoever. A relationship like that can’t last. If Ruth didn’t want him to know, she shouldn’t have kept so many trauma keepsakes. That’s very common, to do that. Did you know that?’

‘No.’

I feel as if I’m hearing the conversation from a distance. It’s like listening to a far-away radio. I could so easily drift out of the range of the voices.

‘Aidan found a box full of souvenirs under her bed, everything she’d kept from Gemma’s trial.’