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.

In 19th Century Paris, the maniacal Dr. Mirakle abducts young women and injects them with ape blood in an attempt to prove ape-human kinship. He constantly meets failure as the abducted women die. Medical student Pierre Dupin discovers what Mirakle is doing too late to prevent the abduction of his girlfriend Camille. Now he desperately tries to enlist the help of the police to get her back.

A US intelligence officer, stationed in Germany, is caught in a political dilemma when the Russians kidnap a young Army private, the son of prominent American businessman. In exchange for the soldier's return, the Russians attempt to barter a trade for an elderly German couple who they want for treason.

In World War I London, Myra is an American out-of-work chorus girl making ends meet by picking up men on Waterloo Bridge. During a Zeppelin air raid she meets Roy, a naive young American who enlisted in the Canadian army. After they fall for each other, Roy tricks Myra into visiting his family, who live in a country estate outside London, his mother having remarried to a retired British Major. Myra is reluctant to continue the relationship with Roy, he not aware of her past.