Policeman Danny Dolan begins walking a new beat at New York's Pier 13. After a boy breaks a warehouse window during a baseball game, Danny chases the young man into a coffee shop, where he meets wise-cracking waitress Sally Kelly, to whom he takes an immediate fancy. Above the coffee shop, Sally lives with her sister Helen and her father, wheelchair-bound ex-sailor Skipper Kelly. At the pier, Danny runs into his friend, detective Al Higgins, who is staking out an arriving ship on a tip that jewel thief Johnnie Hale may be returning from South America on it. Aboard the ship, Hale receives a telegram from his accomplice, Nickie, warning him of a police trap. Dressed as a steward, Hale sneaks by Al, only to be recognized by Danny. Helped by heavy traffic, Hale manages to escape with Nickie in a stolen car. Back at the police station, Danny is promoted to detective and assigned to the Hale case. At the cafe, Helen's sailor boyfriend, Bill Hamilton, arrives with an engagement ring. While working at the Ziegler Importing Company, Helen poses for publicity photos with a $15,000 jade figurine. Hale, recognizing Helen as his old girl friend, plans to steal the same statue. Sally hosts a surprise party for Helen and Bill, but before they can announce their engagement, Nickie arrives at the party and forces Helen to see Hale. At his apartment, Hale blackmails Helen into helping the two steal the jade figurine. Meanwhile, Danny gives Sally a dog named "Bromo" as they begin their stormy courtship. Using Nickie's slight-of-hand, Hale steals the jade figurine by replacing it with a fake. Helen returns home and tells Danny and her sister about the theft. At the police station, Nickie is questioned, as his fingerprints were found on the fake figurine. During the interrogation, Danny discovers a card from the Pier 13 garage, and they deduce Hale is behind the crime. In the meantime, Hale makes arrangements to return to South America by boat. At the pier, he is recognized by a policeman, whom he shoots and kills. He then forces Helen to hide him until his boat sets sail. Back at the coffee shop, Danny proposes to Sally and she accepts, but Danny tells her he must catch Hale before they can marry. He asks Sally if she knows who Hale's former girl friend at Pier 13 might be, but Sally says nothing about her sister. Sally quickly returns home, discovers Hale in the storeroom and learns all. Back at the police station, Danny deciphers Hale's phone number from Nickie's address book and, when searching his apartment, finds the publicity photo of Helen. Back at the Kellys', Hale prepares to leave for his boat just as Danny arrives. Sally hustles Danny out of the apartment, but he goes back on the pretext of returning a book, telling Helen he will protect her if she is indeed involved with Hale. With that, Hale jumps out the window, only to be pursued by both Danny and Bromo. Chased over the roof and back into the apartment, Danny and Hale shoot it out. Danny is wounded while Hale is killed. Promoted for Hale's capture, Danny is questioned about Hale's appearance at the Kelly home. Danny stretches the truth, saying he chased the thief there. Danny finally gives Sally her engagement ring, only to have the two fight over its size.