After Colonel MacFay frantically summons them to his Long Island estate, amatuer detectives Nick and Nora Charles arrive to find the house under heavy guard and the colonel under threat of death by his former employee, Phil Church. Among MacFay's house guests are his adopted daughter Lois and her fiancé, Dudley Horn, who explains that Church blames the colonel for sending him to jail, and the macabre incidents that have been occurring are a result of Church's revenge attempts. That night, the colonel is murdered and Church disappears. As the police interrogate the witnesses, gunshots are heard in the night and Horn is killed. Back in the city, a mysterious caller who promises to produce Church's Cuban accomplice, "Dum Dum," directs Nora to the Rio Club, and Nick, acting on a clue uncovered at Church's girl friend Smitty's apartment, also turns up at the club. There, Nick learns that Church had a second girl friend, Linda Mills, and he goes to investigate her apartment, but finds the girl missing. The next day, Church appears at the Charles' apartment and threatens to harm Nick unless he abandons the case. As he escapes across the rooftops, Church is shot and killed, and the police are summoned. Nick then explains to the puzzled assemblage that Church did not kill MacFay. As he re-stages the shooting, Nick explains that Church's accomplice, Linda Mills, killed the colonel, and Nick then unmasks Lois as Linda. Nick continues that Lois, tired of playing the good daughter, led the life of a moll and killed her father for his money. Once Horn began to suspect her of the crime, she killed him, and Church became her third victim when she began to suspect him of double-crossing her over Smitty.