‘I never take life. Only when my own is immediately threatened.’ The Doctor is back, with a statement of intent. Ever since he vowed to defeat the Daleks a month ago – and which he reiterates here (‘We have got to dare to stop them!’), he’s been a man on a mission, which couldn’t contrast more with Susan’s cosy domestics with David. She’s more worried about some stew going cold than fighting the Daleks. It’s obvious that the Doctor’s outgrown her more than she has him. Fortunately, we’ve had five weeks to get used to the idea of her and David being together – a relationship that’s grown over as many episodes as we might expect even from modern TV.

After last week’s set up, this week is about moving everything towards the climax. Barbara and Jenny have that memorable encounter with the two hags in the forest, who look like they’ve been inspired by the witch in Disney’s Snow White. It’s a really well written, ominous scene, which ends with the Dalek bursting in.

Meanwhile, after dispatching the Slyther, Ian and the Doctor descend into the Earth to uncover the Daleks’ master plan: “Project Degravitate”. It’s barmy but suitably grandiose and apocalyptic. The horror is that to the Daleks, humanity is just an irrelevance: it’s the planet they’re interested in, not us. And given it involves piloting an Earth populated by robotically-converted humans on a journey through the stars, I’m amazed one of the Missing Adventures didn’t posit this as an alternative universe Genesis of the Cybermen.

Next episode: Flashpoint