As a series of mysterious deaths plague Monica Rivers' traveling circus, the first victim, a high-wire performer, is replaced by Frank Hawkins (Ty Hardin), an even more daring aerialist. But Frank's attentions to Monica (Joan Crawford) make her business manager, Dorando (Michael Gough), jealous. After Dorando becomes the brutal killer's next victim, Police Superintendent Brooks (Robert Hardy) arrives at the scene. And when Frank threatens to tell the police that he saw her destroy Dorando's partnership agreement, Monica offers him a share of the circus. When her rebellious young daughter, Angela (Judy Geeson), is expelled from boarding school, she persuades Monica to allow her to stay with the circus. And after Matilda (Diana Dors), an illusionist's assistant, becomes the next victim, and Frank is nearly stabbed to death while doing his wire-walking act, Superintendent Brooks uncovers a clue that exposes the identity of the killer in a surprising climax.