Singer Cab Calloway finds himself in trouble with his jealous sweetheart Minnie when she accuses him of having fallen for his new manager, Nettie. Minnie vows to kill Cab if he runs away with another woman, but Cab silences her rage by striking her. Later, at the Brass Hat Club, while Cab auditions for a spot in a show, Ralph, a booking agent and the owner of the club discuss the shiftlessness of their new competitor, Boss Mason. Ralph tells the owner that Mason is a tough racketeer who plans to open a New York-style club across the street from the Brass Hat. Minnie, meanwhile, plans to take revenge on Cab by enlisting the help of Mason to have him murdered. Mason likes the idea of cutting down his competition, but first tries to lure Cab away from the Brass Hat by pressuring him to sign a lucrative contract with him. Although Cab refuses the offer, Mason gives him half an hour to change his mind. While eavesdropping on a conversation between Nettie and Cab, Minnie realizes that his relationship with his manager has been purely professional all along, and she immediately tries to warn Cab that his life is in danger. Cab, however, rushes off to his next performance before Minnie is able to warn him. Soon after the half-hour deadline expires, Mo, the Mouse, Mason's henchman, is sent to kill Cab, but Cab manages to foil the attempt by grabbing Mo's gun and forcing him out of his hotel room. Moments later, a second attempt is made on Cab's life by Mason, who has been hiding in the hallway. Mason fires his gun at Cab, but the bullet strikes Minnie as she tries to protect Cab. Mason is killed in his ensuing gunfight with the police, and Minnie later dies in Cab's arms. Time passes, and Cab takes the stage to sing a love song about his new romance with Nettie. At the end of the show, Cab announces that he is marrying Nettie, and a reverend appears on stage to perform an impromptu wedding ceremony in rhyming verse.