Murder in the Clouds (1934)

Bob Halsey is a firstrate pilot whos in love with stewardess Judy Wagner Hes ordered to deliver a secret formula to Washington DC but a spy hears about the assignment and sabotages it by murdering Bobs fellow flyers and making off with the liquid While the government conducts a vast search for the formula the spies entangle Judy in their web of deceit causing Bob to set off on his own in an effort to save his sweetheart and retrieve the missing mixture