International arms dealer Anton Kronsky (Paul Lukas) is planning to depart from France in the dead of night aboard the Orient Express. His mission: unknown. Star reporter Patricia Booth (Madge Evans), determined to get the story, steals her editor's "husband and wife" passport to make the trip, as her fiery reporting has made her persona non grata in multiple European states. Meanwhile, novelist Kenneth Stevens (Edmund Lowe), recruited to cover the story by a rival news bureau, loses his passport to a pickpocket. The quick-thinking Stevens passes himself off as the husband half of Booth's passport, much to her chagrin. But while the feuding writers play at newlyweds, their fellow passengers are playing cloak-and-dagger... with murderous intent.