When Janie Prescott's wedding to sailor Sonny Phyffe is delayed because his ship has not yet docked, the wedding ceremony is combined with a christening to accommodate the pastor's schedule. Sonny's father Hector, a lovable swindler, steals a corsage that was intended for his wife, temperamental opera singer Genya Smetana, unaware that the gift from her opera company also included a diamond clip. When Sonny finally arrives on his forty-eight-hour leave, Hector gives him the corsage as a present for Janie, but the wedding is again postponed when Mrs. Prescott announces that Janie's former suitor, wealthy Peter Warrington III, sunk all her money into shaky investments and at the roulette wheel at the 59 Club, and that she is now broke. Despite Peter's deliberate attempts to sabotage Janie's marriage, the wedding proceeds after Sonny, who is not interested in Janie's inheritance, takes up his father's offer to help Mrs. Prescott regain her fortune. Hector arranges with 59 Club singer Leslie Quayle and her boyfriend to "fix" the roulette tables in their favor. Sonny and Janie are about to leave for their honeymoon when Hector insists that Sonny accompany him to the club. There Hector lures his straight-arrow son into gambling, and Sonny and the croupier are astonished by his repeated wins. Hoping again to disillusion Janie, who believes that Sonny is on a government mission, Peter brings Janie, Mrs. Prescott, and Mrs. Prescott's friend, Senator Simpson, to the club. Hector splits the roulette winnings with Leslie, but is then hard-pressed to explain to Genya, who has just walked in, why he is kissing the singer. To allay Genya's suspicions, Leslie and Hector pretend that Sonny, who Genya does not know is her step-son, has just married Leslie. Janie is then astonished to see her new husband dancing with the singer. The confusion mounts when Genya's impresario identifies Janie's diamond clip as the one intended for her, and Genya believes that Janie has married Hector. Hector momentarily distracts Genya by asking the band to play a selection from Genya's favorite opera, Wagner's Tannhäuser . Before they are able to continue their honeymoon, Janie is called on business as an air-raid warden, and Sonny spends the remainder of his wedding night sleeping on the couch. Hector, meanwhile, schemes with Leslie and Eddie to swindle Peter by tricking him into buying worthless stock at an exaggerated price. When Janie returns to Hector's apartment, Sonny leaves and, having read the fake Wall Street Journal provided by Hector, goes along with Hector to the bank to sell the worthless shares, thereby becoming an unwitting accomplice in his father's swindle. Hector then returns to his apartment, and discovers that Janie has moved in, because she mistakenly believes that he was providing the place for her and Sonny as a wedding gift. Genya, who intends to leave Hector, finally learns that he is older than he told her and has an adult son who has married Janie. Mrs. Prescott and Peter then arrive and tell the couple that Mrs. Prescott never lost her fortune but pretended she did in order to test Sonny's sincerity. Peter and Leslie then confirm that the confused bank manager where they transacted the phony stock purchase bought the shares himself. Sonny gives his father the money he got for the shares and finally runs into Janie as he is leaving the building. The newlyweds return to the Prescott home, where the maid, Florrie, suggests that they spend the rest of their honeymoon in Janie's apartment. When the Senator arrives with a new commission for which Sonny would have to leave immediately, Florrie tells him that the couple went out of town, and the newlyweds spend their remaining hours uninterrupted. All of the new acquaintances gather together in Hector and Genya's apartment and sing Wagnerian operas. The cacophany drives Hector to drink, and he is astonished when the characters in Genya's tapestry, which depicts a Wagnerian opera, come to life and flee from the noise.