The exploits of FBI Special Agents Fox Mulder and Dana Scully who investigate X-Files: marginalized, unsolved cases involving paranormal phenomena. Mulder believes in the existence of aliens and the paranormal while Scully, a skeptic, is assigned to make scientific analyses of Mulder's discoveries that debunk Mulder's work and thus return him to mainstream cases.
While on a stakeout of a Government Defense Convention in Las Vegas, The Lone Gunmen are reunited with Susanne Modeski, the mysterious woman who disappeared ten years earlier when they first met Agent Mulder.