Kenny Williams, a homicide detective, realizes that his job is interfering with his love life as everytime he makes a date with his sweetheart Maxine Carroll, the mayor’s secretary, he has to cancel it because of an important case. Tired of being neglected, Maxine tries to convince Kenny to switch jobs. She resorts to desperate means when she reports Kenny to his superior, Captain McGovern, after he shows up for a date handcuffed to a prisoner he was supposed to have escorted to jail. When Kenny learns that Maxine influenced McGovern’s decision to threaten him with suspension for refusing to accept an assignment requiring him to impersonate a woman in order to trap a lady killer, Kenny takes the job just to spite her. One night, Maxine goes out to look for Kenny and is attacked by the killer just as Kenny is ready to pounce on him. After the attack, Maxine finally succeeds in convincing Kenny to quit the police force, but on the day of their wedding, Kenny finds himself back in the fray when a bank is held up and a night watchman is killed. A coloring book found at the scene of the crime leads to the arrest of a man named Stanley, and although Stanley protests that he was forced to open the bank vault while another man shot the night watchman, he is found guilty. Kenny believes Stanley to be innocent and while delivering Stanley to prison, he notices a powder burn on the back of his coat, evidence that could substantiate his innocence. Pulling Stanley from the train, Kenny races to Maxine’s apartment and persuades her to steal from the mayor’s office the bottle that had served as evidence during the trial. The bottle leads Kenny to Reagan, the real criminal, whom he captures at the racetrack. After Stanley is exonerated, Maxine is awarded with the title of special deputy for her help in capturing Reagan, and she and Kenny are married. On their honeymoon night, Maxine insures their privacy by cutting the telephone wires, but when an officer arrives at their home summoning all special deputies to the station, Maxine makes a cheerful and hasty exit. More on Wikipedia or Mubi
Watch The Amazing Mr. Williams (1939)