This episode continues the horror movie overtones of The Tomb of the Cybermen. This time, it opens like a werewolf film, with Traver’s friend John attacked at night by something huge and hairy. The episode makes the most of this strong start by repeatedly implying the next attack is about to come: first, when Jamie glimpses a ‘great hairy beastie’ on the TARDIS scanner – which turns out to be the Doctor in his new coat; then when the Doctor is unconsciously menaced by the looming shape of a Yeti, and then, finally, when Jamie and Victoria come face to face with one in a mountain cave.

After the past few episodes of outer-space adventures, this is a lot more down to earth and contemplative. Troughton responds to this by making the Doctor initially delighted to be back in Detsen, and as pleased as a man with a fancy hat with his new coat. But then, when he sees a Yei footprint, he’s suddenly distracted, and haunted, instructing Jamie and Victoria to remain in the TARDIS while he investigates. This is all very unusual, and adds to the ominous tone.

Wisely, Haisman and Lincoln focus almost entirely on the regulars for the first two thirds of the episode. The Doctor’s discovery of the abandoned campsite and John’s corpse, and his arrival at an apparently deserted monastery are excellent – really adding to the sense of isolation and creeping horror, so that it’s almost a relief when the problematic Tibetan monks (The Talons of Weng-Chiang looks positively woke compared to this) corner the Doctor, Travers accuses him of John’s murder, and he’s locked up pending a decision on his fate.

Meanwhile, things are equally scary for Jamie and Victoria. This is the first episode to properly pair them up for any length of time, and their rapport is great: Jamie very dour, Victoria teasing and teacherly, telling him all about the Himalayas. She’s the one that encourages him to leave the safety of the TARDIS, which ends up with them cornered by a Yeti. The glimpses of the monsters make them seem terrifying – not typically apelike, as in Hammer’s Abominable Snowman film, but oddly birdlike, with huge, owlish heads and scaled feet, and looming hugely over the humans. The cliffhanger view of one lurching towards Jamie as Victoria screams is a new benchmark for horror in the series.

Next episode: The Abominable Snowmen – Episode Two