Dressed to Kill (1980)

In Brian De Palma's erotic Hitchcockian thriller:

• the slow-motion opening sado-masochistic sequence in which upper-class New Yorker and frustrated, sexually-unsatisfied wife Kate Miller (Angie Dickinson) pleasured herself in the soapy shower - she was suffering from a vivid erotic fantasy of being taken, while enduring unsatisfactory sex (a "wham-bang special") with her husband in their bedroom

The Opening Shower Fantasy-Rape Sequence

• the brilliant 10-minute sequence in the Metropolitan Museum of Art of Kate's cat-and-mouse flirting with a nameless stranger (Warren Lockman (Ken Baker))
• the sequence of Kate's taxi-cab seduction en route to the man's apartment
• the horrific murder sequence in the elevator of a high-rise apartment building when she was brutally assaulted by a black-coated woman (spoiler: her transsexual psychologist Dr. Robert Elliott (Michael Caine)) in a blonde wig and dark glasses wielding a sharp straight-edged razor

Kate Miller's Elevator Slashing Murder

• the murder of Kate was witnessed by high-class prostitute Liz Blake (Nancy Allen); determined to solve the murder, Liz found herself questioning Kate's psychologist/counselor Dr. Robert Elliott; Liz and Kate's clever son Peter (Keith Gordon) schemed together to set up traps to track Dr. Elliott's patients; at one point, they entered Elliott's office where Liz sexily stripped down to her black lingerie, when she was attacked by the knife-wielding "Bobbi"
• the remarkably tense finale - a plot-twisting shower nightmare scene experienced by Liz - she dreamed that the insane and vengeful doctor had escaped from a mental hospital after strangling a nurse, and wore the nurse's white shoes as disguise; he killed her with a sharp razor blade after she had stepped out of a shower -- similar to the violent rape/sex fantasy scene in the film's opening shower scene - however, Liz woke up screaming (and holding her neck) to end the film