The X-Files: 10 Best Mythology Episodes

Throughout the show's first season, the main story arc was fairly vague and mysterious, only offering up slithers of information that pertained to the existence of extraterrestrials and a shady cabal that was puppeteering the American government.

This smattering of information was enough to keep fans invested but it wasn't until 'The Erlenmeyer Flask' that it became essential viewing for the initiated. This episode is a particular standout because it took all of the intrigue and tension of previous mytharc episodes and cranked it up to new heights.

It's clear from the outset that the showrunners wanted to end things with a bang and everything from the opening car chase, to the scene in which Scully infiltrates a military research facility to acquire an alien foetus, feels like a much bigger and bolder version of the show. Subsequent season finales would up the budget and intensity with varying degrees of success, but there's something so brilliant about this smaller story that has big repercussions - most notably on informant Deep Throat who is callously gunned down during its climax.

It was a heart-stopping episode that changed the show's foundations forever, placing Mulder and Scully within the eye of the storm and firmly establishing that from here on out, nobody was safe.