Ruth Rendell's Thirteen Steps Down

Mix Cellini is a lonely young man who is employed by a company that repairs exercise equipment. He lives in a flat of an old Victorian house in Notting Hill. His reclusive landlady, Gwendoline Chawcer, spends her time reading and thinking about lost loves. Mix becomes obsessed with serial killer John Christie and a local model, Nerissa Nash, despite the fact that she never acknowledges his existence.