Billy "Big Bang" Blitz is a sergeant in a tactical ops group called S.A.B.R.E. (Special Assault Brigade for Real Emergencies). He and his fellow operative Mary are recalled from leave to deal with an emergency situation: Professor Plum, creator of a Doomsday Bomb capable of destroying the world, has been abducted by an army of ne'er-do-wells. Bang soon encounters Tom Guycot, the mastermind behind the professor's abduction. He also learns from his dying friend Joe that the Doomsday Bomb is controlled by six medallions which have been distributed among Guycot's minions, the governors of Demonhead. Traveling through the game's various routes, Bang faces down the governors and acquires their medallions.