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.