At the tail end of 1917, the Germans introduced a new type of gas to the battlefield, T-Leiche, or "corpse gas," and changed the face of the war by resurrecting the bodies of the dead, giving the enemy an almost unlimited source of fresh troops.

When the American ace Major Jack Freeman—poster boy for the war against the Kaiser's undead army of shamblers—is downed over enemy lines and taken captive, veteran Captain Michael "Madman" Burke is the only man brave and foolish enough to accept the mission to recover Freeman. Burke assembles a team of disparate members, from his right-hand man, Sergeant Moore, to big-game-hunter-turned-soldier Clayton Manning, who funds the mission for an opportunity to confront this most dangerous zombie game, to professor Dan Richards, one of Tesla's top men and the resident authority on all things supernatural. With the help of a highly advanced British dirigible war machine to infiltrate enemy territory, the team faces incredible danger as it struggles to reach the prison camp and strike at the heart of the enemy.

But they are pitted against the most deadly enemy of all: Manfred von Richthofen, the Red Baron. Having risen from the dead with his abilities enhanced but his mind on the brink of madness, Richthofen has plans for victory that give no quarter to soldiers or civilians.