While baby-sitting in a hotel, a beautiful woman (Marilyn Monroe) begins a flirtation with one of the hotel's guests (Richard Widmark). Rebounding from a breakup with his girlfriend (Anne Bancroft), he's willingly seduced by the baby-sitter and ends up in bed with her. When the child wakes up and disturbs their lovemaking, the baby-sitter reveals homicidal tendencies and terrorizes them both. A frightening and provocative exploration of a murderer's mind.