An American woman arrives in Hong Kong to unravel the mystery of her missing photogrpaher husband. After getting nowhere with the authorities, she is led by some underground characters to an American soldier of fortune working in the area against the Communists. He promises to help find her husband

In the early 1950s, American Jane Hoyt travels to the British crown colony of Hong Kong in an effort to locate her husband Louis, who has been missing for three months. There, consulate worker Frank Stewart explains to Jane that Louis, who illegally entered Communist China to take photographs for a magazine, is probably being held captive, and that inquiries made by the American government have gone unanswered. Jane then checks into the Peninsula Hotel, where she attracts the attention of various residents, including French gigolo Rene Dupont Chevalier. In the morning, Jane meets British marine police inspector Merryweather, who found Louis' abandoned cameras months earlier. Merryweather explains that the boat captain who took Louis to China was uncooperative, and bitterly remarks that most of the junks are controlled by American Hank Lee. Despite Merryweather's description of Hank as a dangerous smuggler, the desperate Jane asks to meet him. Merryweather discourages her, instead telling her to go to Tweedie's bar, which was frequented by Louis. That night, Jane goes to the bar, where she is saved from Tweedie's hostile threats by Rene. After Rene reminisces about Louis and reveals that he occasionally drank with a man named Fernand Rocha, Tweedie brutally states that Louis is dead. The next day, Jane visits Maxine Chan, who also knew Louis, and asks for an introduction to Hank. Maxine calls Hank, and that night, Jane is taken to his mansion in the hills. Jane is surprised to be greeted by a young Chinese boy named Billy Lee, and to learn that Hank, despite his dubious reputation, is devoted to the three orphans he has adopted. Hank and Jane are instantly attracted to each other, although the pragmatic Hank tells her that her $7,000 is not enough to make him risk entering China. When Hank kisses her, Jane realizes that he would be willing to help if she offered a more intimate reward, and storms out after calling him a "lonely shell" of a man. The following day, Jane walks through Hong Kong, questioning anyone who might have known Louis, but learns nothing. Exhausted and frustrated, Jane goes to Hank's office and accepts his dinner invitation. While eating, Hank states that he is willing to locate Louis in order to become a legitimate rival for Jane's affections, and Jane, unable to hide her attraction to Hank, warmly takes his hand in gratitude. Unknown to the couple, a man photographs them and the picture is shown to Louis, who is being held in a dank prison. Louis' interrogator, Needle, refuses to believe Louis' explanation of his presence in China, and intimates that he is an American spy and will lose his wife to Hank. Back in Hong Kong, Hank orders Tweedie to find out whatever he can about Louis, and also asks for help from Dak Lai, an ancient Buddhist priestess. Meanwhile, Jane learns from Rene that Rocha runs a language school in Macao, and immediately books passage there. When she arrives at the school, Rocha tells her that he needs money to bribe Louis' captors, and the naïve Jane gives him a $500 travelers' check. In Hong Kong, Dak Lai's friend, Catholic priest Father Xavier, informs Hank that Louis is imprisoned in Canton. Hank is beginning preparations to take his personal junk, the Chicago , to Canton when he learns that Jane has been taken captive by Rocha. Pressing Rene into service, Hank distributes a truckload of watches to the "water people" who live in junks in the harbor. On the Chicago , captain Yink Fai is preparing to sail when Merryweather, intrigued by his activites, boards the vessel to inspect it. Below deck, Merryweather uncovers an anti-aircraft cannon, and when Hank boards, tells him that the junk will be impounded because of the illegal weapon. Merryweather is surprised by Hank's jovial acceptance, but after the junk sets sail, realizes that he is being abducted. Upon reaching Macao, Hank goes ashore and beats Rocha into revealing that Jane is upstairs. Hank happily reunites with Jane, and after sending her to Hong Kong with Rene, reboards the Chicago and informs Merryweather of their mission in Canton. Although he knows that he will be fired for participating, Merryweather readily agrees, and sneaks ashore with Hank and Yink Fai. With Hank and the inspector concealed in crates, Yink Fai and truck driver Keim go to the prison. Louis watches from his cell as Keim and Yink Fai pretend that the truck has broken down, then knock unconscious the guard who approaches them. The men succeed in freeing Louis, but as they reach the Chicago , an alarm is sounded and the military pursues them. Recognizing Hank from the photo, Louis questions his motives for helping him, and although Hank will not admit it, Louis realizes that he and Jane are in love. Later, when Hank and Louis are talking, Louis confesses that he will never be able to give up seeking adventure. After they reach the open sea, a Chinese patrol boat shoots at them, so Hank and Louis return fire with the cannon. Despite its power, the gun falls short of its target, while the Chinese weapons begin pounding the junk. Suddenly, dozens of junks appear, steered by the water people to whom Hank gave watches. When the Chicago disappears in the crowd of vessels, the Chinese are forced to stand down, and the water people wave their watches at Hank. Later, Hank watches from a distance as Louis and Jane leave the hotel, then goes to a lonely tram stop overlooking the city. Jane surprises Hank by joining him, and reveals that Louis has decided marriage is not for him. After Jane tells Hank that she is in love with him, the couple stand arm-in-arm and look over the harbor.