Rittmeister Hans Von Hammer, known to the allies in World War I as the Enemy Ace, is shooting down allied planes over Cambrai. He and his Fokker airplane down multiple planes, but is just unable to destroy a plane before it drops its payload. The allied plane destroys a supply train, and flying through the flames causes the canvas wings of Von Hammer’s Fokker to catch aflame. Regardless, the Enemy Ace shoots down the plane as it flies away.
Von Hammer returns home, his plane limping from fire damage. Called the “Hammer of Hell,” Von Hammer is praised by his fellow pilots. However, they do not understand how the Enemy Ace thinks. To Von Hammer, this is the cold need of the hunt: there is no emotion involved in what he does, nor does he ask for quarter from his foes. Von Hammer’s point is driven home by a wolf that coldly kills a bear.
Back in the sky, the Enemy Ace meets his arch-enemy, a Canadian Nieuport 17 pilot he has named the Hunter. After the Hunter chases off two German planes, he drops a note to the Enemy Ace. The note mentions the cowardice of the pilots he chased away, and he will face them again. Enemy Ace, with the two German pilots in tow, takes off. Enemy Ace salutes the Hunter, which passes the symbol that this is to be a duel only. The Hunter, who lives by the same code of honor that the Enemy Ace does, acknowledges. The Hunter duels the two cowardly pilots, and kills them easily. When the Hunter and the Enemy Ace leave, they know they next time they meet, the duel will be between the two of them.
Many days and many missions later, the Enemy Ace sees the telltale plane of the Hunter. The Hunter again drops a note: it is time for the two of them to duel. The Enemy Ace takes to the sky, and engages the Hunter in a dogfight unlike any other. The two planes shoot each other down, and even after the crash, the Enemy Ace and the Hunter duel on the ground with pistols. The Enemy Ace wins, but is saddened for the defeat of such a talented foe.