The X-Files #1.3: Squeeze
“Squeeze” is the first monster episode of The X-Files! And a pretty good one. It was very creepy, and did a good balance of Scully Explanations with Mulder Explanations.
A series of murders where the victim’s liver was taken out are discovered, with no visible point of entry into the room by the murderer. Mulder realizes this series of murders happens every 30 years going back to 1903. All this is shown with cool shots of the murderer, Tooms, crawling through small spaces. In the end, he goes after Scully directly, but Mulder catches on and they stop him before he steals her liver. Show ends with Tooms in a hospital room, eyeing the tiny food tray hatch in the door, and smiling. Surely, he gets out!
There were two things made particularly clear in this episode. First, Mulder is a genius. Second, Scully really likes working with him on these cases.