An American in London, down on his luck, runs into a beautiful blonde in a bar who offers him a lot of money to marry her. Broke and unemployed, he takes her up on it. When he wakes up the next day, he finds himself in a strange room that turns out to be an artist's studio, there is blood on his coat, and he discovers that his new "wife's" father had been murdered the night before.

While American Casey Morrow is quietly getting drunk in a London nightclub, he is approached by a young woman who offers to buy him a drink. After Casey tells her that he is broke, they leave the club together and she states that she will give him five hundred pounds if he will marry her. The next morning, Casey wakes up in artist Maggie Doone's studio and is unable to remember what happened after he and the woman left the club. Maggie tells him that she had never seen him before he rang her door bell early in the morning. Although Casey sees a portrait of the mystery woman in the studio, he leaves without asking Maggie about it. On the street, he sees a newspaper headline stating that Darius Brunner has been murdered and that his heiress daughter, Phyllis, is missing. A photograph of the daughter reveals that she was the woman Casey may have married the night before. After Casey finds a large sum of cash in his coat pocket, he returns to Maggie's studio and tells her that he thinks Phyllis murdered her father and is trying to frame him for it. Maggie tells him that Phyllis had modeled for her but had lied extensively about her family background, then shows him a magazine announcement of Phyllis' engagement to prominent young lawyer Lance Gorden. Posing as a newspaper reporter, Casey goes to Gorden's office, but discovers very little and ends up slugging Gorden. When Casey returns to Maggie's, he finds Phyllis there and accuses her of framing him. Phyllis explains that when they returned to her apartment the previous night, they discovered her father beaten to death with a poker. Casey had stumbled over the poker and picked it up, thereby putting his fingerprints on it and getting blood on his coat. Phyllis then dumped Casey at Maggie's. Phyllis swears that she did not kill her father, but thinks Gorden did. As the police are beginning to connect Casey to their investigation and he hopes to prove his innocence, Casey agrees to let it appear that he and Phyllis are married and they rent a small flat. Casey then poses as an insurance investigator and talks with Brunner's secretary, who tells him that Gorden handled many charity donations for Mrs. Brunner. After Casey takes Phyllis to meet his mother, who is remarried to an English pub owner, he goes to see Phyllis's mother. She tells him that she is aware that Gorden may have acted improperly in regard to her charity donations. Casey then discovers that Travis, Gorden's henchman, has killed a private detective hired by Phyllis's father to investigate the charity fraud. When Casey goes to see Gorden, he finds him with Phyllis and her mother and Phyllis offers Casey ten thousand pounds to disappear. Later, after Gorden tries to kill Casey but is shot by an unseen assailant, Casey confronts Phyllis and accuses her of killing Gorden. However, the killer is revealed as Mrs. Brunner, who also killed her husband and the detective because they had discovered that she had been setting up fake charities and draining her husband's fortune. Mrs. Brunner holds Casey at gunpoint and intends to frame him. She has already called for the police, but Casey, although wounded, overpowers her. After Casey is cleared by the police, he and Phyllis intend to marry for real.