Deep beneath the Nebraska prairie lurks a vast bunker that has lain undisturbed for nearly four decades. Built by Tony Stark's long-lost father to survive a global holocaust, the subterranean city is accidentally discovered by a young boy who then gets lost in its depths. The modern-day Iron Man has to come to the rescue. Can he discover the reasons behind his father's mysterious disappearance too? Unfortunately, the complex is defended by an army of original gray Iron Man armor automatons, which could spell Armageddon for the Armored Avenger!