After Peiping is bombed by the Japanese, American passengers on an ocean liner bound for Shanghai are advised not to continue unless it is absolutely necessary. Del Forbes, a soldier of fortune, tries to talk naïve Joyce Parker, a would-be journalist from Sacramento, into returning, but she remains. When Maurice Zabello, an ailing gunrunner, offers Del $10,000 to impersonate him in Shanghai and collect £200,000, nearly one million dollars, from Joseph Lang for a cargo of munitions, Del accepts. In Shanghai's International Settlement, an area governed since 1843 by thirteen foreign nations for trade purposes, Del registers as Zabello at a hotel, whereupon the clerk informs Monte Silvers of the Far East Export Company. In his room, Del is shot at by Lenore Dixon, who thinks he is Zabello, but she misses and he disarms her. He offers not to call the police if she will have dinner with him that night, his only evening in Shanghai, and she agrees. In the hotel lobby, Del runs into newsreel cameraman Wally Burton talking with Joyce, who has been unable to get a room. Del invites them to join him at Ferrold's, where Lenore sings, and then goes with a hired man to meet Lang. After receiving custom certificates for the munitions from Del, Lang gives him a money belt filled with the pounds sterling, despite the suspicions of Lang's Scottish partner Murdock. On their return to the settlement, the hired man is knifed to death and Del is held up, but he gets away and finds his way to the ship only to learn that Zabello has just died from heart failure. Wanting to return the money to Lang, but unable to locate the building where they met, Del goes to Ferrold's, where Lenore suggests that they meet later at the Green Dragon, at which time they can begin the night as if they have just met. Lenore tells Silvers about the date, and during dinner at the Green Dragon, Del explains his predicament. Lenore reveals that she wanted to kill Zabello because he murdered her father, a Nicaraguan official. Now concerned for Del's safety, Lenore takes him to see Lang. After learning from a spy of their plans, Silvers gets to Lang first with his men. They kill Lang and wound Murdock, who escapes, before Del arrives. Silvers then demands the belt and tells him that Lenore, who is waiting outside, is working with him. During a fight, Del is shot in the arm. Just then the city is bombed by the Japanese, and as Lenore comes into the room, the roof collapses. Silvers escapes with the money belt, and Lenore awakens to find Del unconscious and pinned under a beam. She brings a doctor, who gives Del a transfusion with Lenore's blood to save his life. When Del revives, he pushes Lenore away in disgust and collapses. While she searches for help, Del revives again and escapes the building. Lenore finds Wally and Joyce, but when they arrive back at the building, they find it in flames and believe that Del has died. After Americans are warned to leave Shanghai, Lenore and Joyce board a ship, while Wally remains, promising to visit Joyce in Sacramento. Lenore finds Del on the boat, but he walks away from her. However, Joyce tells him about the transfusion, and he goes to Lenore's cabin, where he finds her with Silvers, actually her estranged husband. Lenore gets Silvers' gun and orders him to give the money belt to Del. Silvers is then killed by the near-dead Murdock, who succumbs himself. Finally, Del reminds Lenore of the Chinese saying that if one saves a life, one is afterwards responsible for that life.