The plot revolves around the player character, a marine known as the "Doomguy," who is stationed on Mars at the Union Aerospace Corporation (UAC) research facility.
The UAC has been conducting experiments involving teleportation and interdimensional travel, seeking to harness the energy from Hell itself. As the plot unfolds, a teleportation accident occurs, unleashing hordes of demons and turning the facility into a nightmarish realm. The protagonist becomes trapped in the facility and must fight for survival while uncovering the sinister secrets behind the demonic invasion.