When the U.S.S. Missouri docks in San Pedro harbor, sailor Jimmy Harrigan makes a telephone call for his pals, Barnacle Benny Cohen and Bilge Moran, to their sweetheart, Minnie Broadhurst, who, on their last visit, broke a number of chairs over their heads. Instead of Minnie, Jimmy reaches twenty-one-year-old Sally Brent, who hangs up on him when she learns that he is a sailor. As the three sailors arrive at the boardinghouse where Minnie used to live, Sally, who must move unless she can pay her rent, is leaving to apply for a job at the nearby Crystal Pool. Jimmy follows her, chased by a banana seller whose merchandise was stolen and eaten by the sailors, and then by Benny and Bilge, who have been chased out of the boardinghouse because of the broken chairs. At the pool, Sally is immediately offered a job by the philandering owner, Nugent Busby. She slips into Busby's wife Mona's bathing suit and tries to teach Jimmy to swim, although she does not know how herself. Mona then enters, and in the ensuing uproar, a number of people are thrown into the pool fully dressed. Sally leaves before Jimmy, who later hitches a ride with the extremely besotted J. Felix Hemingway. After Jimmy spots Sally on the street, Hemingway takes them to dinner, during which she and Jimmy dance and get to know one another. Because Sally now has no place to stay, Jimmy rents a room for the night. Sally nervously avoids his advances and attempts to go after he kisses her, but instead Jimmy berates and spanks her for letting a guy get her a room and leaves himself. The next morning, he returns with food and, after a couple of kisses and a confession that he loves her, leaves for his boat, promising to return that evening. Jimmy's ship, however, sails for San Francisco, and he is unable to inform Sally. Meanwhile, Sally evades the persistent advances of the owner of the apartments, Baron Portolo, who offers to let her win the first prize of $1,000 at the upcoming dance marathon that he is promoting. She also agrees to babysit for Junior, the son of Elmer Brown, who lives down the hall. That night, when Jimmy calls from San Francisco, Portolo speaks into the phone, and Jimmy hangs up thinking Sally is cheating on him. The next day, Jimmy returns and rushes to the apartment with presents of women's undergarments to apologize, but when he sees Brown in a robe leaving Sally's apartment, he insults her and rips the undergarments to pieces. Stung sharply, Sally agrees to enter the marathon. Jimmy, meanwhile, learns that Sally told him the truth about babysitting for Junior. When he hears Portolo over the radio announce Sally's entrance in the marathon, Jimmy runs to the dance hall, where he is thrown out by Portolo's gang. He climbs a tree and crashes through a window to get in again, and after taking the willing Sally away from her partner, socks Portolo and sets off a riotous fight between sailors and the gang. In their departing cab, Jimmy slips a wedding ring on Sally's finger, and they kiss as each grabs the other's hair tightly.