Doctor Who episode 177: The Abominable Snowmen – Episode Four (21/10/1967)
Haisman and Lincoln avoid the pitfalls of many six-part stories by spacing out the revelations and making sure each episode feels like a concrete step forward rather than simply a restatement of what the audience already knows. This starts with the resurrected Yeti rampaging through the monastery, features some mid-episode tension as the Doctor and Jamie face Yeti on the mountainside, and finishes with the reveal of Padmasambhava.