Joy Ling and Tommy Wong are in love, but their families have been feuding for hundreds of years and their fathers forbid them to marry. The day after four more killings occur in a continuing tong war between the Lings and the Wongs, Tommy risks his life by entering the Ling house in order to ask Joy's father, Lieu Ling, if he may marry Joy. Ling rebuffs him, but later Ling and Wong meet and agree to settle the peace with a valuable jade necklace, which Tommy will give to Joy. When The Daily Herald reports that the necklace, worth $50,000, is going to be presented that day, a pair of thieves named Harry and Raymond team up with a crook named Zamboni, who is an acquaintance of Ling. Ling agrees to let Zamboni record the peace ceremony and wedding for the Ling and Wong relatives in China to announce the end of the feud. Meanwhile, Bob Martin, Chinatown reporter for The Chronicle , reports to work with his talented dog Tarzan and is upbraided by city editor Butler for not having picked up the Ling-Wong story. Although Butler sends Bob out to cover a polo match with his girl friend, reporter Ann Parker, Ann gets an interview with Joy. While Bob is called away to cover a fire, Ann witnesses the peace talks while Zamboni sets up the recording equipment upstairs at the Ling's home, which is also their antique shop. Harry and Raymond, meanwhile, are parked at the curb outside, waiting for Zamboni to make his getaway with the necklace. When Joy goes into her bedroom and admires the necklace in the mirror, Zamboni, who has knocked out Li Foo Ling and taken his robe, accosts her just as Tommy enters. Zamboni stabs Tommy, then runs upstairs with the necklace. Tommy is sure that a Ling has stabbed him, and the feud is immediately resumed. Ann, meanwhile, goes upstairs and sees that the killer is Zamboni, but he locks her in the room that contains the recording equipment, then discards the Chinese garb and knife and hides the necklace in a decorative box. Raymond and Harry, suspicious of Zamboni, enter the shop and accuse Zamboni of double-crossing them. Bob, meanwhile, writes a note to Ann and orders Tarzan to take it to her in her office. When Tarzan finds her missing at the paper, he goes to the Lings' home, carrying the note in his mouth. At the same time, the Ling men meet and, by process of elimination, decide that it was Li Foo who stabbed Tommy. Fearing for their lives, Joy and her father huddle in the shop as the Wong men enter. One of them hurls an ax at a curtain and inadvertently kills Harry. Tarzan, meanwhile, approaches Ann's room from the roof, and she quickly records a message for Bob, then, breaking the skylight, hurls the record through it. Tarzan then runs back to Bob with the record in his mouth. Bob listens to the message, in which Ann pleads with him to come quickly and tells him that she loves him. Raymond, meanwhile, beats up Zamboni, who tells him that Ann has the necklace. Ann quickly locks herself in the room before Raymond can get to her, while Bob and Tarzan race to the scene. Bob breaks the skylight and descends just as Raymond breaks in and accosts Ann. While Tarzan fights Raymond, Bob catches Zamboni trying to retrieve the necklace and apprehends him. Ann then hears knocking in a trunk and discovers Li Foo, whom she frees. Tarzan brings Raymond's gun to Bob, then retrieves the necklace and chases Zamboni outside. There Tarzan locks Zamboni in a cellar. The police arrive, having been notified of the renewed Ling-Wong violence, and arrest Zamboni. Ling explains the mistaken accusation of Li Foo to Wong. The feud is again called off and the necklace is restored to Joy. Bob then calls in the story to Butler and is about to insult Gilmore, the paper's owner, whom Bob calls "Old Walrus," when Ann informs him that Old Walrus is her father and that Parker is only her pen name. Bob then asks Butler to ask Gilmore if he can marry his daughter, and Bob and Ann kiss.