Mary Barrett is an aspiring opera singer who is taken under the wings of a famous operatic maestro, Guilio Monterverdi. After spending endless working hours together and arguing, their relationship develops into love. But, jealousy and misunderstandings prevent Mary and Guilio from acknowledging their true feelings.

In the waning days of WWI, a U.S. "Mystery Ship," sets sail for the coast of Spain towing a submarine. Their mission is to find and sink a U-boat that has been especially effective in attacking Allied shipping. Posing as a harmless schooner, the mystery ship is in fact fitted with a formidable gun capable of sinking a U-boat. Stopping in the Canary Islands to refuel, the crew interacts with locals involved with Germans, and with Germans themselves, including the sister of the U-Boat commander, who is lurking offshore waiting for the coming battle.

In the Austrian manor of Baron and Baroness von Burgen, the relationship between the upstairs aristocracy and the downstairs staff is quite positive. The servants seem to enjoy their time together, and some even fall in love, as head butler Albert and maid Anna have done. But when lecherous new chauffeur Karl Schneider enters the house, affairs and blackmail follow, and the harmony of the home is slowly destroyed.

An American doctor and his wife, a former singing star, witness a murder while vacationing in Morocco, and are drawn into a twisting plot of international intrigue when their young son is kidnapped.

A hard-working mother inches towards disaster as she divorces her husband and starts a successful restaurant business to support her spoiled daughter.

Philo is in Vienna working for the US Government to see if Archer Coe is selling aircraft designs to foreign powers. He grabs the plans with Archer's signature, but is captured by police before he can escape. Deported he comes back to America and plans to confront Archer, but Archer is found dead in his locked bedroom with a gun in his hand. While it looks like a suicide, Vance knows better and the coroner finds that Archer has been shot, hit with a blunt instrument and stabbed - making suicide unlikely. But Vance is on the case and is looking to see if government secrets have been sold and who has murdered Coe. This is a remake of "The Kennel Murder Case" using aircraft designs and espionage instead of Chinese porcelain and dog shows.

A prominent New York doctor, unable to have a child, discovers her philandering husband has impregnated her best friend.

A large caravan of settlers attempt to cross the Oregon Trail. German-language version of The Big Trail (1930) with an alternate cast and co-director. Bill Coleman (named Breck Coleman in the U.S. version) leads settlers in covered wagons Westward, across the prairie and mountains.

Ambassador Joseph Davies is sent by FDR to Russia to learn about the Soviet system and returns to the US as an advocate of socialism.

Jeffrey wants to marry Virginia, who refuses to marry unless her older sister, the hard-to-please Angelica, gets married first. This is the German language version of Buster Keaton's comedy "Parlor, Bedroom and Bath" (1931).