QQ4 - The Web of Fear 4

What a shame that this episode doesn't exist anymore, mostly because of the full-on action battle sequence (still a rarity in those days) between the army and the Yeti. Directed by Douglas Camfield, I'm sure it looked spectacular, although I wish he'd chosen different stock music to punctuate the scenes instead of the music that had already been made famous as the theme for the Cybermen in all three Cyberstories to date.

The outcome of the battle, as well as the fact that not only is anybody wandering around the Underground outside of the army base in extreme danger, but now that the Yeti are crashing into the base and wiping out soldiers, not even inside the base is safe from the Yeti. Lethbridge-Stewart has the dubious distinction of losing both his first platoon in the Underground before we even meet the character, and then, later, in the battle with the Yeti, he loses all the soldiers under his command there, too. (And he gets promoted later?). The Yeti appear to be the most invincible enemy that The Doctor has ever come up against, even more so than the Daleks.

Further more, there's suspicion that someone in the base is working for the Yeti (or, more directly, the Great Intelligence), but we still don't know who it is. And when Travers finally shows up at the end of the episode, apparently possessed himself, almost all hope is lost as the credits crash in. Episode Four has been one of the most wonderfully dark and bleak episodes of Doctor Who ever made. And also one it the best.