The film begins with William Castle introducing the movie, saying this is about some insane people. Then, after the title comes up we go to 1948, to a house where a young girl is playing with her doll. Her mischievous brother comes in and steals the doll from her. In the next scene the movie goes to present day (1961), where a blonde woman, Emily, checks into a hotel. She offers to give the bellboy two-thousand dollars if he'll marry her the next day. She says the marriage will be annulled the following day. He figures he has nothing to lose and needs the money. They get married late at night and wake up the justice of the peace. But right after the hasty wedding she pulls out a knife and repeatedly stabs the old man. Then, she returns home, leaving her stunned groom behind.
Emily is the caregiver for an old paralyzed, mute woman named Helga. Helga has a son named Warren, who is a businessman, and a step-daughter named Miriam. Warren is to inherit ten million dollars from his father's Estate in two days, on his 21st birthday.
But Emily continues to act irrationally and continues to mentally abuse Helga and cruel to Miriam. She even tells the sister that she and Warren are secretly married, which Warren admits when she confronts him about it. However, Miriam thinks something is really screwed up about Emily so she contacts the police. There's an article in the newspaper about the justice-of-the-peace being killed and the drawing of the killer is a dead-ringer for the woman. But in order to prove it she needs the groom to identify her...
Right before the ending, when the "twist" is revealed and the reason why Emily is so nuts, there's a break. The Fright Meter comes up, which has the sound of a beating heart, and gives the audience members a chance to leave before the shocking ending, if they choose. And the ending is a humdinger, up their with Castle's STRAIGHT-JACKET. It's especially weird, considering this was made forty years ago. This unique thriller is included on the dvd WILLIAM CASTLE FILM COLLECTION.