Billy Holmes, an American aviator, is assigned to a unit of the Royal Flying Corps involved in constant action over the western front and during his initial encounter with the enemy is accused of cowardice. When he meets Mimi, a charming little French girl, Billy is inspired to boast of his bravery in action. During a skirmish between the unit and a squadron of German airplanes, Red McGibbons, an ace and close friend of Billy's, brings down the brother of Lebrun, leader of the Hun force, but is himself killed. Lebrun challenges the Allies to an air duel, and Billy accepts the challenge despite Mimi's objections. Although he is forced to the ground by the experienced Lebrun, as is his friend, Sven, Billy miraculously escapes injury, pursues the German in another plane, and downs him. After the Armistice Billy returns home with Mimi as his wife.