One Breath is, as far as X-Files mythology is concerned, the episode immediately following Ascension (3, a vampire tale, takes place between the two, but is a standalone story, though it does address the absence of Dana Scully). It sees the return of Scully following her abduction, albeit in a vegetative state, which leads to her family and Mulder reaching an impasse about whether to take her off life support (something put to rest by the terms of her living will). It also sees one of the most emotional scenes in X-Files history: Mulder placing a gun to the head of the Cigarette Smoking Man, his shadowy antagonist, after being tipped off to his location by his immediate superior, Assistant Director Skinner. Their exchange is one of the best of the series, and the Smoking Man's warning of "Don't threaten me, Mulder - I've watched presidents die" is one of the most chilling lines in the entirety of the show's history. This sort of tight writing made One Breath a standout in the season.