I know this is generally viewed as a cheap and rubbish story, but there’s a level of detail over some of the sets and costumes that shows a touching amount of effort. The market place has a little fountain, the idol face of Amdo and the hieroglyphics suggest an ancient culture with African and South American roots, and the visual signifiers – the scientists in lab coats, Zaroff’s guards in wetsuits, priests in Lionfish headdresses and robes, and the Atlanteans in their elaborate shell costumes – differentiate each class. Partly converted Fish People wander round the market, and the stallholders worry about their goods. It’s hardly Star Wars, but this world does feel more complete and lived in than the planet of the Savages.

There’s a bit more going on this week than last, which means less onus on Troughton to carry it. But the characterisation of the Doctor continues to settle down, even if he gets one of the last of his disguises. There’s a lovely moment where they are about to be beheaded and he apologises for getting Ramo into this, which reminded me of the fifth Doctor’s apology to Peri in The Caves of Androzani.

The basic plot is a mix of the familiar and the weird. Provoking revolutions has been a stock-in-trade for the show since Ian and the Doctor encouraged the Thals to rise up against the Daleks, but it’s a really odd choice, especially given my previous comments about finding three companions something to do, to see Sean inciting the Fish People to go on strike, while Ben and Jamie run round in wetsuits. The resulting “Dance of the Fish People” goes on a bit too long, but is the kind of strangeness that’s been a bit lacking in the show since Innes Lloyd took over (only the Mondassian Cybermen are quite this weird).

Zaroff is a bit more of a familiar character – but it’s odd to see a mad scientist surrounded by a primitive society: the closest thing in the show previously is the Monk’s arrival in medieval England. In general, this is as bonkers as At The Earth’s Core. Much of this episode focuses on him (for once, the capture/escape trope applies to the villain), and Joseph Furst rises gleefully to the occasion: furious with the super-camp priest Lolem (who prissily curses him), devious enough to fool Ramo and Polly, and getting the notorious cliffhanger:

ZAROFF: Nothing in ze world can stop me now!!!!

Next episode: The Underwater Menace – Episode 4