Star Trek: Darkness Within is a Star Trek-themed MUSH set in the mirror universe during the period between the Enterprise television show and the original series of Star Trek. Since the majority of the details during this period (and in this timeline) are unknown, we follow canon as much as possible and have a unique history to fill in the many gaps.

The year is 2199, and the Terran Empire rules the majority of space with an iron fist. Having conquered most of the major powers, the Terran Empire's reach extends throughout the galaxy. Laying siege to those who stand in their way, the Terran Empire is feared throughout the alpha and beta quadrants. Within the last ten years, however, a growing force of resistance has become a thorn in the massive paw of the Terran Empire. Battles between the Imperial Starfleet and the resistance dot the blackness of space with brief flashes of explosions and death. Independent factions hope not to get involved, and resistance members try their hardest to rally support for the cause.

With reports that the Empire has finally been able to reconstruct a Constitution class warship from the plans of the futuristic USS Defiant (NCC-1764), the resistance may have a tough time standing up to the firepower of this new threat. Will you fight for the glory of the Terran Empire as an officer in the Imperial Starfleet? Will you side with the rebellion and lead covert missions into enemy space to secure the freedom of your race? Or will you be a wealthy merchant dealing in trade goods and secrets? Without the light, there can be no shadow - only the darkness within.