When a British army officer, Harry Faversham, resigns his commission on the eve of his regiment's departure for service in the Sudan he is sent four white feathers of cowardice by his comrades and fiancee. In an attempt to redeem himself, Faversham travels out to the Sudan where he saves the lives of his former comrades.
A frightened woman is murdered in the London apartment of a well-known novelist named Henry Leroux. The police arrest Leroux's butler, but he escapes and runs off to a mysterious opium den, the lair of a drug dealer named Mister King. Gaston Max, a detective from Paris, arrives in London to investigate the drug trafficking. Although the police take down the gang, Mr. King escapes and manages to keep his true identity a secret.
Arthur Doublon a mechanic nicknamed Chignole by his army buddies is soon to become an aviator. He is betrothed to Sophie Bassinet whose dad is a coachman and mom is a janitor in Montmartre. On their way to Nancy, Chignole and his lieutenant, Old Charles, meet an American soldier from the Lafayette Escadrille. Soon afterwards, Chignole's dog, Boudoubadabou, is wounded by a shell burst and Racine, their mechanics, is killed by an enemy plane. Chignole jumps into his own plane and shoots the enemy. He gets a medal for his act of bravery but is moved to the infantry as a discipline measure.
