In the spring of 1939 in England, Oxford University Professor Richard Myles and his new bride Frances decide to honeymoon on the Continent. Because they are American tourists and therefore "above suspicion," they are commissioned by the British secret service to find a scientist who has developed a countermeasure against a new Nazi secret weapon, a magnetic sea mine. Without knowing his name, what he looks like, or where to find him, the couple look upon the search as an adventure and cross Europe seeking clues from clandestine contacts. In Paris, Frances is given a hat decorated with a rose as a signal for their first contact, who silently instructs them to go to a café in Montmartre. An unseen contact plants a tourist guidebook to southern Germany in Richard's coat. The couple notice a series of ink dots on a map in the book, which, linked together, form a musical staff with the opening notes to the song "My Love Is Like a Red, Red Rose." They deduce this is their password. Three pinpricks in the same map direct them to the book's seller, A. Werner, in Salzburg. Werner instructs them to go to a certain museum. There a man named Count Hassert Seidel, calling himself a "guide," suggests that they check into a guest house run by Frau Kleist. She provides them with a book on Franz Liszt with annotations that reveal their next stop should be the village of Pertisau in the Tyrol, where they should inquire about a doctor who collects chess pieces. Some days later, the couple intends to go to a performance of Liszt but are advised against it by Thornley, a fellow houseguest and recent graduate of Oxford. They go anyway. During the passage that Thornley had been practicing earlier, a Nazi colonel, the Commandant of Dachau concentration camp, is shot and killed. Officials insist on questioning each member of the audience. Richard and Frances are rescued by Gestapo Chief Count Sig von Aschenhausen, a former Oxford schoolmate of Richard's. Thornley later tells Richard that he killed the Nazi colonel as revenge for the torture and murder of his Austrian fiancée. He also warns Richard that he and his fiancée had also once been "above suspicion." Frances and Richard go to the home of chess collector, Dr. Mespelbrunn. While he does not appear, Count von Aschenhausen does. They notice sheet music for "My Love Is Like a Red, Red Rose" on the piano. But when Sig fails to respond to a code signal that Richard gives him, the couple becomes suspicious. They hear thumping noises upstairs and discover that Sig is holding Mespelbrunn prisoner. Mespelbrunn tells them to run and says they are being hunted by the Gestapo. The couple leaves the housejust in time, and Count Seidel arrives to help them free Mespelbrunn. He is revealed as the missing scientist "Dr. Smith". All four head for Innsbruck, and Mespelbrunn gives Richard the plans for the countermeasure. The couple obtain counterfeit passports from an elderly couple named Schultz. They are planning to catch the train to Milan at separate stations; but, when the Schultzes are arrested by the Gestapo, the police are on the lookout for the Americans. Frances is detained and questioned by the Gestapo; but Thornley, in Innsbruck to catch the same train, finds Richard. Richard, Thornley, and Seidel gain entry to where Frances is being held and kill her captors, including Sig; but Thornley is also killed. After fooling the Nazi border guards, Seidel and the American newlyweds reach freedom in Italy.
Variety wrote, "Both MacMurray and Miss Crawford completely handled their roles, despite drawbacks of script material", and T.S. in The New York Times commented, "Joan Crawford...is a very convincing heroine." Critic Howard Barnes wrote in The New York Herald Tribune: "There are so many floral, musical and cryptographicalpasswords in the film's plot that the whole show becomes a sort of super treasure hunt... Unfortunately, neither Joan Crawford nor Fred MacMurray looks quite bright enough to unravel the tangled skeins of this screen melodrama."
The film was released on Region 1 DVD on April 6, 2010 from the online Warner Bros. Archive Collection. This film marked the end of Crawford's 18-year career with MGM before signing with Warner Bros. It was the last role for character actor Conrad Veidt, who died of a heart attack a few weeks after shooting ended.
