Joe Rogers goes undercover in order to expose a murderer named Mrs. Gillespie. He believes that she has been killing her husbands for insurance money. He discovers that Mrs. Gillespie has a fiance and plans to marry again. He also discovers that she has taken out a large insurance policy on him. Later, Mrs. Gillespie runs off on another honeymoon. Joe meets another man who happened to be investigating Mrs. Gillespie's fiance. Apparently, he has had four previous wives, each of whom died under mysterious circumstances.