‘The circle must be broken.’ Four years in the new series finally gets round to doing a proper alien planet that’s not just a quarry at night or a CGI city. The Ood-Sphere looks great, and is the biggest selling point about a story that otherwise feels like it’s a draft away from being finished.

My big problem with it is that the Doctor and Donna spend the run time wandering about discovering things as they’re happening, watching a long-laid plan come to fruition and standing by as Ood Sigma’s patient preparation of Halpen pays off, before swooping in and seemingly claiming credit for unlocking the Rani’s Brain and freeing Ood-kind from slavery: the ultimate unearned white saviours. Had they not arrived there on a whim, events would have played out almost exactly the same except Ood-Halpen would have been the one to switch off the telepathic dampening field. The result is, bafflingly, much more like an old-school historical than The Fires of Pompeii. In the previous episode, the Doctor and Donna had to make history happen, here they just observe it.

The story of a revol-ood-tion, an enslaved population with a very inhuman biology held back from realising their potential by Earth exploitation, makes this The Mutants of the 21st Century. Like The Mutants, a human scientist has been secretly helping the Ood. And like The Mutants, there’s an irony in casting BAME actors to play many of the whip-hand roles. The point, I suppose, is that human skin tone variations are meaningless when the Second Great and Bountiful Human Empire has spread across three galaxies and conquered species as odd as the Ood.

Unlike The Mutants, there’s not much more to it than this. Some of the incidentals are quite good – particularly Donna’s sympathy for the Ood (although some of her early “isn’t this brilliant” schtick is a bit much). The music is lovely. The Ood remain fun. Some of it’s weak: the long set piece of the Doctor being chased by a grabber isn’t as exciting as it seems to think, and Ood-Halpen fondly recalls Dalek Sec. It drops some plot points for later in the series – the Doctor-Donna; the Doctor’s song ending; the disappearance of the bees. But mostly it’s just there, the kind of unremarkable rebels versus imperials story that bulked out most of the 1970s seasons.

Next Time: The Sontaran Stratagem