In this silent film, romantic rivals fly against the enemy in World War I.

In 1917, in a small American town, Jack Powell tinkers on a car, while daydreaming about airplanes. When the car is roadworthy, Jack names it "Shooting Star" and Mary Preston, the girl next door who helped him, paints a star on the side of the vehicle. Oblivious to the infatuated Mary's feelings for him, Jack invites a more sophisticated city girl, Sylvia Lewis, to accompany him on the first drive. Sylvia rides with Jack, but she is in love with David Armstrong, the son of the town's wealthiest family. Later, when the United States enters World War I, Jack and David enlist and apply to aviation school. Before they leave, Sylvia signs a picture of herself and puts it in a locket for David, but when Jack sees it and thinks it is meant for him, she does not have the heart to contradict him. David, who returns Sylvia's affection, is hurt, but she takes him aside and explains that, although Jack has her picture, David has her heart. Jack almost forgets to say goodbye to Mary, but then runs back to shake her hand and give her permission to use the car. While saying his farewells to his mother and wheelchair-bound father, David finds a favorite old toy, a tiny bear, which he decides to take with him for good luck. During basic training, an antagonism develops between Jack and David, which is finally resolved in boxing class when they are paired off in a heated practice bout of boxing and become fast friends. After Jack and David complete ground school, they are bunked with Cadet White, an affable and experienced young flier. Upon seeing David's bear, White comments that many fliers have mascots, although he does not, as he believes, "when your time comes, you're going to get it." He then leaves for flight practice during which he dies in a plane crash. Later, when Jack and David are sent to France, Jack paints a star-shaped logo on his plane like the one on his car. During their first patrol, the fliers encounter Capt. Kellermann, a famous German ace and leader of the "Flying Circus." At 10,000 feet in the air, a dogfight ensues, during which both German and Allied planes are lost. David's machine gun jams as he is singled out for an attack, but his opponent chivalrously spares his life. Jack becomes separated from his formation and is attacked by two German Fokkers, forcing him to crash-land and abandon his plane. He survives, and takes refuge with entrenched British ground soldiers. Meanwhile, Mary, who has learned to drive the Shooting Star and has joined the Women's Motor Corps of America, is sent overseas to transport medical supplies. She is driving toward flu-stricken Mervale, where billeted regiments crowd the little village, when a Gotha, the mightiest of German bomber planes, attacks. Jack, David and their colleagues come to the rescue during an aerial battle, and shoot down the Gotha and its two escort planes, thereby saving the village. As they fly away, someone points out to Mary the shooting star on the side of one of the planes and Mary realizes that Jack had been there. For their accomplishments, the pilots are decorated as heroes and given a furlough in Paris. To escape the horrors of war, Jack carouses with a Folies Bergère performer. Mary, who is also in Paris, finds Jack at the Folies too drunk to comprehend when all leave is cancelled in preparation for the Allies' "big push" against the Germans. Mary tries to tell him about the change in his orders, but in his inebriated state, Jack sees only her uniform and sends her away. While the rejected Mary is in the ladies' room crying, a sympathetic attendant advises her to "catch the fly" with "sugar, not vinegar," then takes her backstage. Later, provocatively attired in a show girl's costume, Mary seduces Jack away from his female companion and takes him to his hotel room, where he falls asleep on the bed before she can get him sober. While she is changing back into her uniform, military police rounding up the men walk in and conclude that she has been moonlighting as a prostitute. Jack is returned to his unit with little memory of his night of revelry, and Mary is arrested and sent home in disgrace. Back at the base, while waiting for orders, David has a premonition that he will not return home. Upon reading in the newspaper that Mary has resigned from the corps, Jack expresses surprise that Mary would quit. When fellow pilot Lt. Walter Cameron suggests that she was fired for sexual misconduct, Jack takes offense and David watches as Jack hotly defends her reputation. Having received numerous love letters from Sylvia, David hopes that Jack's affection has turned to Mary until Jack shows him Sylvia's locket. Believing that Sylvia shares his feelings, Jack says that her picture is his good luck charm. When the picture falls from the locket, David reads the inscription on the back dedicated to him, which Jack has never seen. Unable to put it back without Jack seeing it, David is ready to fight his friend for the photo, rather than let him be hurt by the truth, but they are interrupted by orders to board their planes. They take off without resolving their quarrel and without their respective good luck charms, as David's bear has also fallen from his pocket. The pilots are sent to protect ground troops who are under attack from German fliers. David hurls himself into danger to protect Jack from attack and later crashes near the Mad River in German-occupied territory. After successfully evading the Germans that night, near dawn Jack steals a Fokker from an airfield, hoping he can fly it back to his base. Meanwhile, presuming that David is dead, Jack vows to avenge him. After daybreak, he and his comrades fly out to assist the advancing Allied ground soldiers as the war is waged both in the air and on the ground. When David flies to the scene, Jack spots his plane, but sees only the German cross on the fusilage and does not recognize his friend. Although David tries to call out to Jack and evade his single-minded assaults, Jack shoots down his plane, which crashes into a church. Feeling victorious, Jack lands, but discovers to his great shame and grief that he has fatally wounded David, who forgives him before dying. After the war, Jack is welcomed home as a hero with parades and other festivities, but must carry out one more war-related task. Ashamed and grieving, he returns David's medal and little bear to the Armstrongs and receives forgiveness. Later, Mary comes to sit with Jack near his car and they talk for hours. By evening, when they see a shooting star in the sky, Jack realizes that he loves Mary.