Suspended airman James Dawson, called "Flash," works for a gang of smugglers who move Chinese across the Mexican border for a high price. When the pilot of plane "X-26" is unable to land because of police patrolling the airfield, the shipment of Chinese isn't delivered to smuggling chief Chin Chu, and he refuses to pay Flash and accuses him of murdering his countrymen. In revenge, Flash informs on the smugglers, tipping off veteran police inspector Sullivan to raid a gambling house called the Canton House, where Chin Chu and his gang meet. While he is on the phone, Flash is shot to death by one of Chin Chu's men, causing Sullivan and Morgan, his partner in the Immigration Service to race to the Canton House with backup policemen. Among those being corralled into paddy wagons is Viola Avery, daughter of Judge Avery, who has been up all night playing fan-tan. When a mysterious curio collector rescues her from Sullivan, insisting she is the judge's daughter, Viola is grateful and agrees to attend his cocktail party the next day. Meanwhile, police chief Graves breaks up the ineffectual team of Morgan and Sullivan and pairs Sullivan with rookie investigator Baxter to solve the informer's murder. Suspicious of the woman who claimed to be Viola Avery, Baxter calls her, and when she comes to retrieve her purse, he drives her home and questions her about the strange man. At the Avery home, Viola and Baxter are met by a throng of reporters, but Baxter staves off a scandal by informing the press that Viola's implication in the raid was a case of mistaken identity. Baxter then tells her father that she was with him the previous night and promises to meet her at the curio collector's cocktail party. Later, Baxter deduces that the informer was a grounded pilot who recently began flying again, and orders Sullivan to identify him. Using the name Keeler, Baxter poses as an aficionado of Oriental law and gets himself invited to the strange man's party whose name he learns is King Moss. During the party, Moss is visited by one of his henchmen, Spud Nolan, who informs him they are short a pilot for the next run of Chinese. At the party, Viola tells Moss and Baxter that her father locked up her plane and revoked her license and that she would love to fly with Moss. Meanwhile, Sullivan has identified the corpse as Flash, and he and Baxter go to Flash's apartment, where they find a hole in the newspaper want-ads. Tracing the paper, they discover that Flash answered an ad for an aviator who is "fearless and ready to take a chance." They also learn that the day after Flash's death, the same ad appeared in all the papers around town. Hoping to identify the smugglers, Baxter goes undercover as gangster pilot Tricky Thomas and meets the smugglers at an Acme Trucking Company warehouse. Spud gets suspicious when one of his men tells him that the real Tricky is in jail and calls in a gangster named Steve to identify Baxter. When Spud tells Moss their new flier might be a phony, he asks Viola to make a secret flight with him to his "ranch," warning her she might have to fly the plane back alone. Meanwhile, Baxter tries to escape by knocking out Rod, one of the guards, but a thug named Tiger enters and helps Rod tie up Baxter. Across the border, Chinese liaison Yung Yow insists Moss leave a hostage to ensure a safe passage for his countrymen, and Moss agrees to leave Viola. When Viola realizes she is a hostage, she escapes and takes off in the plane filled with Chinese, which Moss pursues. Meanwhile, at the warehouse, Steve exposes Baxter as a fake and Sullivan calls for backup and raids the warehouse, saving Baxter just as Rod is about to shoot him. Sullivan and Baxter then go to Mercer Field to meet the shipment and arrest Spud. Baxter goes up in a plane and orders plane X-26 to land. When Baxter discovers Chinese in the plane, he tells Viola he will have to arrest her, but she insists she was a hostage. Baxter then goes up in his plane to bring down Moss and shoots down his plane and arrests him. Baxter confiscates half of a letter written in Chinese from Moss, and Sullivan matches it with the one he found on one of the Chinese. With their evidence intact, Sullivan prepares to resign, but Baxter handcuffs Viola to him and tells him to report to Graves that he eloped with the secret agent who helped him solve the case.