Thad Walker (Tab Hunter) is a young man from a good Boston family, but he's spoiled, rebellious, and always at odds with his strict father. When Thad gets into trouble with the law one time too many, his father strikes him. Thad leaves his home and joins up with other American volunteers heading for the front lines of World War I. Since the U.S. is not at war yet, Thad joins the French Legion. The American volunteers in the French Legion are trained as fighter pilots for the Lafayette Escadrille. During his training, Thad proves he's a skilled flyer, but his temperament prevents him from taking orders and being obedient. When he strikes a French drill officer, Thad faces the prospect of a court-martial and a minimum sentence of ten years in prison. Discouraged, he deserts and runs away to Paris, where he first fell in love with a pretty French girl named Renée Beaulieu (Etchika Choureau). They live together in her small hotel room and eventually get unofficially married. But the French Police are looking for deserters and Thad feels like a prisoner inside the hotel, afraid to go out in public where he could be seen by policemen. Meantime, his American pals from Lafayette Escadrille finish their pilot training and get their wings. Thad tries to get a job in Paris, working as a bodyguard and driver for the girls of a local Madam. When America finally enters the war, many American officers arrive in Paris. This is how Thad meets a U.S. General (Paul Fix) in a Paris cab. He decides to plead with the American General to allow Thad to serve in the newly formed United States Army Air Service, despite the fact that Thad is technically a deserter from the French Legion. Moved by Thad's plea, the General pulls strings to have Thad recruited into the Air Service. Thad finishes his fighter pilot training, gets his wings, and is sent to fierce frontline combat against German fighters. In Paris, his French wife wonders if she'll ever see him alive again.