Picking up immediately after the events of the original Doom, the lone space marine known as Doomguy escapes the moons of Mars through a demonic portal, only to arrive home to a nightmare. The forces of Hell have poured onto Earth, slaughtering billions and reducing the planet to a ruined battleground. The scattered survivors of humanity have devised a desperate plan: build a fleet of massive spaceships to carry what remains of the human race off-world to safety. But there is a catastrophic problem. Earth's only functioning ground spaceport has been seized by the demons, who have thrown up an impenetrable energy barrier that traps every ship on the surface. Standing alone against the horde, the marine must carve a path through the demon-infested city and cripple the barrier, buying humanity its one slim chance to flee the doomed world.