What do you think about my book idea?

Well, I've just written a chapter and I want to get people's opinions on it to see if it's worth continuing. Basically the title is called Therapist, but the word will be split into The Rapist. It is basically this hypnotherapist who hypnotises his patients and sleeps with them. They wake up, not fully aware of whats happens so they say nothing about it. One woman however, was not completely under, so as he tries to touch her, she puts up a fight. He ends up killing her to cover her tracks, which is where the police come in. That's the idea so far, like I said, I havent gotten very far writing it yet.