A former secret agent, now a private investigator, is hired to protect a beautiful film star and gets involved with gun runners. Detective Jerry is about to reveal to Maggie the results of the investigation she entrusted to him. It is then that he is shot dead, before the eyes of Maggie, herself being pursued by gangsters who miraculously spare her. She asks Claire Kronski, a lawyer, and Matt Helm for help. Maggie tells her story: her father was murdered when she was six years old. He was an officer and had discovered the clandestine activities of one of his sergeants. She has sworn to avenge her father and wants to find the culprit. He would be living in the United States under a false identity and would have altered his face...

Helm is hired by a charming socialite with a dual personality to investigate a murder that she may have been committed while acting as her other self.