Doom 3: The Lost Mission

More than six hours has passed after the invasion has started. The last surviving Marine team, Bravo Team, makes their way through the Enpro Facility before a horde of demons ambushed them. One survivor barely escapes from his team's carnage. The Bravo team survivor is contacted by Dr. Richard Meyers, a scientist working on teleportation experiments in Exis Labs, and asked to help Meyers destroy an experimental teleportation array that was captured by the demons and is currently held deep inside Hell. The array is potentially powerful enough to send an army of demons all the way to Earth, hence Meyer's desperation to destroy it. To achieve this goal, the marine must acquire the components necessary to activate the Exis Labs teleportation system, then travel to Hell in order to destroy the teleportation array.

The Lost Mission is the second official Doom 3 expansion pack, released in 2012 as part of Doom 3: BFG Edition. The player takes control of a surviving member of the marine squad Bravo Team, which the hero of the original campaign was meant to rejoin. The primary objective, given to the marine by Dr. Richard Meyers, is to shut down a high-powered long-range teleporter in the top secret Exis Labs in order to prevent the demons from using it to reach Earth.