Catacombs begins with a crowd lining up to see an exhibit on a culture and religion that predates any recorded civilization. The player catches a glimpse of four people about to become heroes in event scenes before entering the museum. All eyes are on a mysterious object in the center which emits a flash of light. Monsters suddenly fall from the ceiling and the floor crumbles. Creatures mercilessly slaughter patrons and some security guards while Catacombs’ four heroes are consumed by a purple haze rendering them unconscious. When the heroes awaken, they find themselves as some of the last survivors. Two security guards come to their rescue and try to fend monsters off as the group runs to an elevator. The heroes are saved, but the guards perish and one of the panicked heroes frantically presses the close door button. The elevator jumps from floor to floor until a cord snaps and the lift freefalls to the bottom of the museum. The four puzzled heroes emerge from the rubble and find themselves in a twisted labyrinth.