Tough, smart Eddie Darrow, on an assignment for Philadelphia gangster Bernie Pendleton, arrives in Macao to search for his ex-girl friend, Christine Lawrence Manard. Although Eddie claims to hate Christine, who left him two years earlier to marry Manard, a rival gangster who has since been slain, Pendleton mistrusts Eddie and sends henchman Cliff Chalmer to tail him. Eddie's first act is to visit a nightclub that Christine frequents. There, he rescues club owner Justin Keit from an attack by Chinese thugs. Justin feels indebted to Eddie but, upon hearing his name, invites him to his palatial home, and there carefully watches Eddie as he introduces him to his fiancée, who turns out to be Christine. Later that night, Justin secretly listens as Christine explains to Eddie that Manard coerced her into marrying him by threatening to hurt Eddie, and then, after the gangster was killed, she also became a target and was forced to flee the country. Although Eddie initially refuses to listen, he eventually softens and urges her to be wary of Justin, whom he suspects of racketeering. Christine insists that Justin is a good man and begs Eddie to leave. At breakfast the next morning, Justin, hoping to keep an eye on Eddie, offers him a security position at the nightclub's casino. After a few weeks at work, Eddie is befriended by sharp-eyed piano player Allan. On Christine's birthday, Justin brings her to the club and has the band play Eddie and Christine's song, noting their discomfort. Later that night, Christine and Eddie try to talk but he is disgusted with her dependence on Justin and spurns her. He then apprehends a man with a gun striding toward Justin's office, after which Justin claims that the man was after gambler Hon-Fai, who just obtained a line of credit. Minutes later, however, Hon-Fai is robbed of thousands of dollars and murdered, and Eddie realizes that, instead of credit, Hon-Fai received money from Justin. He brings Christine home, where, after a brief fight, he pulls her to him for a passionate kiss. When Justin returns home that night, he sees that Christine has been crying, and subtly warns her not to hurt him. Confused, she escapes out the back door to Eddie's apartment, where he reveals that he was hired to bring her to Pendleton. She informs him that the gangster wants to kill her because she wrote an affidavit, now locked in her safe-deposit box, containing details about Pendleton's illegal dealings with Manard. Eddie promises to spirit them both out of the country, but when Christine leaves hours later, she finds a furious Justin waiting outside. The next day, Justin pretends to leave on a trip, allowing Christine and Eddie to plan their escape that night. Minutes before she is to meet him at his apartment, however, Justin shows up with henchman Sam. All three are shocked when Chalmer enters, pretending to be a pal of Eddie's. As soon as Justin leaves, however, Chalmer, who knows about Eddie's plans to hide Christine from both Justin and Pendleton, punches Eddie. Eddie lies that he is merely duping Christine into traveling back to America with him, but Christine is listening outside and, sure that he has double-crossed her, flees back to Justin and marries him. At the wedding reception at the club, Eddie tries to convince her that he was lying to Chalmer, but she does not believe him. That night, however, she listens while Chalmer threatens to kill Justin, revealing that Eddie lied to him to save Christine. Just before he can kill Justin, Sam shoots Chalmer, and Christine races out the back door to Eddie's. Allan, who is also there, reveals himself to be a secret agent. He gives the couple a list of Justin's international accomplices and instructions to stow away on a boat to San Francisco. Justin and his henchmen catch up with them just as they board the boat. On the deck, Eddie knocks out first Sam and then Justin. He grabs Christine and they sprint off the boat, while at that very moment Sam, who is lying on sacks of gunpowder, reaches for his gun. Eddie and Christine watch from the dock as his gunshot causes the boat to explode into flames. Days later, Eddie and Christine sail toward home. Although they do not know that reports of Christine's death have resulted in the discovery of the dossier and Pendleton's subsequent indictment, Christine nonetheless trusts Eddie's intuition that everything will work out.