I’d say this one’s an anomaly, because it doesn’t really make enormous sense, but actually it’s not really. It’s incredibly typical. This is Doctor Who at its most simple in terms of classical “space adventure,” and 90% of it is The Doctor and Jo being kidnapped and placed in interchangeable prisons. Ostensibly you get multiple prisons, one an episode — and it’s tied together by a malevolent conspiracy organized by someone working behind the scenes, so the villain doesn’t even really have to show up for the entire thing, pretty much. And it’s all about two factions who can’t agree with each other, like every other Classic Who serial. In modern Who, you’d have this whole thing be erased by the psychic paper, and I sort of yearn for that thing throughout. The Ogrons, our supposed threat, are very scarce, and so, actually are thrills, at least until the Master shows up.

So the whole thing is buoyed entirely by the impressive performances of the lead characters, who by this point have developed their dynamic to a fine art, and the surprisingly good dialogue that shows up whenever the story isn’t doing technobabble and space exposition.

Look at the scene with The Doctor and Jo discussing the fallibility of mind probes with an anecdote about a pink elephant. Look at the scene with Pertwee escaping while Jo natters on endless entertaining dialogue to distract the Master. The gags in this are rare, but they’re so good and witty you’d begin to think they were written by Steven Moffat.

This is very subpar Doctor Who, so “gun” it hurts, with hardly an original idea in the package, especially if examined from a modern lens. But, and this is an important but, it’s also Doctor Who with all the main performers at the top of their game. Pertwee, Delgado and Manning are all transformative. For brief, glimmering moments, it’s an extraordinary blast.