Kay Murdock (Lynn Bari) strolls into the Dixie Bar in Shanghai on November 1, 1941 and asks the bartender for a letter addressed to Captain Larsen, and is referred to Roy Bonnell (Preston Foster), the manager of this combination bar and gambling house. He refuses to turn the letter over to her and she steals it. Bonnell later recovers the letter which contains a coded note. Kay reveals she is an agent of the British Secret Service. Bonnell, a fugitive from American justice, says he will turn over the note to the highest bidder. When he approaches the Japanese, they seize him but he escapes, after learing that the note was part of an alarm for Japanese fifth columnists everywhere after the attack on Pearl Harbor that has just been set in motion.