The X-Files S04 E05 The Field Where I Died

"The truth is out there."

After an FBI raid on a doomsday cult called the "Temple of the Seven Stars", Mulder meets Melissa, a cultist who claims to have known him in a previous life during the American Civil War. Scully believes the woman is a delusional schizophrenic, but Mulder allows himself to be drawn into her fantasies.