‘Before we start your treatment and talk about the impulses that drove you to kill, we need you to understand your options.’

Do I have any? They seem very limited at this moment.

‘You can, if you wish, walk out of this door right now. If you implicate us in any way – tell anyone that we tried to protect you – we will deny it. There is no evidence at all of our involvement. We’ve taken care of that.’

I want to ask what they have done with the claw hammer and my clothes. Maybe if they no longer exist the police will have no evidence to hold me. But Thea has already said that the police have named me as a suspect, and given that I have no idea what happened that night, there may well be other evidence at the house.

‘Your second option is to trust us and to stay here under our protection. I think Thea has explained what we would expect in return. We are both getting on in years, and help around the house would be useful. In addition to that help, I would want you to agree to some treatment with me. I am fascinated by the mind of the killer, and as a psychiatrist I would like to leave a legacy of understanding for my colleagues. For as long as evil has existed, people have wondered about its source, and I would like to explore it with you. For that to work, you will have to learn to trust me implicitly.’

He thinks I’m evil. Oh my God! What a dreadful thought. But why he would let me live in his house if he thinks that? I have no answer, but it doesn’t matter because he answers my question for me.

‘I don’t think we’re at risk from you. I don’t believe you killed for the pleasure of killing, and Ian had pushed you to the edge of sanity. You killed to remove the source of your distress.’

I’m appalled by the idea that I have done something so dreadful to rid myself of a problem, but I have to consider what the doctor said. He has offered me two options, and with every cell in my body I hope he is about to offer me another, more appealing choice. But he is quiet. I feel he is waiting for me to speak.

‘I appreciate so much what you are doing for me,’ I say quietly. ‘But how long can this last? Will there come a time when it will be safe for me to leave?’

‘There is no statute of limitations on murder, Judith,’ he says. ‘Any time you leave here, you are in danger of being arrested.’