Some meddling kids steal the TARDIS and leave Romana at the mercy of a spider. In between, K9 gets decapitated (which is almost too horrible, except Romana immediately says he can be repaired) and the Doctor meets the Deciders (including new member George Baker) as if they’re the judges in a TV talent show.

A lot of work has been put into this; the details are brilliant – like Romana handing Tylos back his knife, or the Doctor cheerily greeting the melodramatic Deciders. The characterisation is good: Login’s anguish over his daughter’s rebellion, and his subsequent decision to repress his personal feelings and accept his wider responsibilities towards the community feel almost like something from a Play for Today (it helps that George Baker is injecting some credible emotion into the part). I don’t understand why the Outlers are so aggressive towards Romana, but I suppose it’s meant to show their impetuosity and fear. Peter Grimwade’s direction has some nice touches: the close ups of the Marshmen look good even if it shows they’re a bit rubbery.

So far, then, this is all-round solid. What it’s lacking is a spark of Adamsian wit, or a true frisson of Holmesian black comedy. Even the Hinchcliffe stories were funny as much as they were horrifying. The show’s rarely been quite this sombre in the past – a few of the early Hartnells, The Massacre, bits of Season Seven. This haunting solemnity, as much as anything else, is what makes Season 18 so distinctive.

Next episode: Full Circle – Part Three