Bruno Stachel (George Peppard) is a corporal in the German infantry who leaves the fighting in the trenches to become a fighter pilot in the German Air Service. Joining a squadron in spring 1918, he sets his sights on winning the highest decoration, the Pour le Mérite, nicknamed the "Blue Max", for which he must shoot down 20 aircraft. Coming from humble origins, Leutnant Stachel is driven to prove himself better than the aristocratic pilots in his new fighter squadron, especially Willi von Klugermann (Jeremy Kemp). Their commanding officer, Hauptmann Otto Heidemann (Karl Michael Vogler) is an upper-class officer whose notions of chivalry conflict with Stachel's ruthless determination. On his first mission, Stachel shoots down a British S.E.5, but does not receive credit for his "kill" because there were no witnesses. He searches the French countryside for hours in a pouring rain looking for the wreckage, giving the other pilots the impression that he cares more about it than the death of the man he flew with. Soon afterwards, he attacks an Allied two-man observation aircraft, incapacitating the rear gunner. Then, instead of downing the helpless victim, he signals the pilot to surrender and fly to his base. However, as they near the airfield, the wounded man revives and reaches for his machine gun, unseen by the admiring observers on the ground. Stachel is forced to shoot the aircraft down, but Heidemann believes Stachel simply murdered the crew in order to gain a "confirmed" kill.

The incident brings Stachel to the attention of General Count von Klugermann (James Mason), Willi's uncle. When the general comes to the base to award his nephew the Blue Max, he meets Stachel. As a member of the masses, "as common as dirt", the pilot has great potential for propaganda purposes. That night, the general's wife, Kaeti (Ursula Andress), mistakenly enters Stachel's room. She is carrying on a discreet affair with her nephew by marriage, with her husband's knowledge. Soon afterwards, Stachel is shot down going to the aid of a red Fokker Dr.I attacked by two British fighters. He survives the crash landing. When he returns to the airfield, he is stunned when he is introduced to the man he saved: Manfred von Richthofen, the Red Baron. Grateful, von Richtofen offers Stachel a place in his squadron. He regretfully declines. With Stachel temporarily grounded owing to a minor injury, General von Klugermann orders him to Berlin to help shore up crumbling public morale. While there, von Klugermann invites Stachel to dinner so that Kaeti can sleep with her latest hero.

When Stachel returns to duty, he and Willi von Klugermann volunteer to escort a reconnaissance aircraft. British fighters attack. Stachel's guns jam, but Willi downs two of the enemy on his first pass, then a third on Stachel's tail, and the rest disengage. As the two are returning to their base, Willi challenges Stachel. Spotting a bridge, Willi dives under the wide middle span, but Stachel tops him by flying under a much narrower side one. Seething, Willi clears the smaller span, but clips the top of a nearby brick tower and crashes. When Stachel reports his death, Heidemann assumes that the two verified victories were Willi's. Insulted, Stachel impulsively claims the kills, even though it is discovered that he had only fired 40 bullets. Outraged, Heidemann reports Stachel's lie to his superiors, but is told that Stachel's victories will be confirmed. Later, during a strafing mission covering the retreat of the German army, Stachel disobeys Heidemann's order not to engage enemy fighters; one by one, the rest of the squadron follow him. Afterwards, Heidemann has Stachel arrested, furious that nearly half the pilots were killed in the ensuing dogfight. Stachel, however, cares only that he has shot down enough aircraft, even without Willi's kills, to qualify for the Blue Max. The two men are ordered to Berlin. There, General von Klugermann tells Heidemann privately that Stachel is to receive the Blue Max. Heidemann resigns his command in disgust when the general orders him to withdraw his report; he accepts a desk job.

Later that evening, the countess visits Stachel and suggests that they run away to Switzerland since Germany's defeat is inevitable. She storms out when he refuses to be one of her "lapdogs". The next day, Stachel is awarded the Blue Max by the Crown Prince in a well-publicized ceremony. However, a field marshal telephones von Klugermann to inform him of an impending investigation into Stachel. The general asks how the field marshal found out about Stachel's lie. While listening on the phone, he turns his gaze to his wife. Desperate to avoid a scandal, von Klugermann sees a way out when Heidemann reports that the new monoplane he has just test-flown is a "death trap", with fatally-weak struts. He orders Stachel to take the aircraft up and to "show us some real flying." During strenuous aerobatics, Stachel's aircraft breaks up, plunges to the ground and bursts into flames. Von Klugermann stamps and signs Stachel's personnel file and has it sent to the field marshal, stating, "It is the personal file of a German officer and a hero."