The X-Files - Season 4 - Eps 21: Zero Sum
After a swarm of bees mysteriously kill a postal worker in an enclosed restroom, Assistant Director Skinner covers it up by destroying the evidence. In order to complete the task he poses as Agent Mulder, however his deception backfires. When Mulder finds out and confronts him, Skinner reveals that he is working for the Cigarette-Smoking Man in order to obtain a possible cure for Scully's cancer.
About The X-Files

Title: The X-Files
First Air Date: 1993-09-10
Last Air Date: 2018-03-21
Status: Ended
Rating: 8.4/10 (from 3182 votes)
Language: EN
Seasons: 12
Total Episodes: 218
Network: FOX
Genres: Mystery, Sci-Fi & Fantasy, Crime
Production Companies: Ten Thirteen Productions, 20th Century Fox Television
Synopsis
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.
Cast

David Duchovny
Fox Mulder

Gillian Anderson
Dana Scully

Mitch Pileggi
Walter Skinner