Verity Lambert’s final Doctor Who episode is really strange. For various contractual reasons, she had to deliver an episode without any of the regular cast being available. This is the result: a story where the TARDIS never appears, the Doctor doesn’t turn up to save the day, and the Daleks triumph.

This is great in one respect, because after their slightly jokey treatment in The Chase, here the Daleks are as dangerous as they’ve ever been, populating a planet with more of the mutated flora and fauna of Skaro to act as security guards, and ruthlessly exterminating their enemies. Before they even appear onscreen, Terry Nation’s script builds them up as a credible, even semi-legendary menace. Space Security agent Marc Cory (‘Licensed to kill’) talks about what the Daleks have been up to in the thousand years since their invasion of Earth – the gradual incursions into various constellations, rebuilding their strength and even re-appearing in the Solar System.

Nation also introduces body horror to Doctor Who. The Vargas are the first of numerous creatures that mutate humans and turn them into hideous monsters. This is particularly disturbing as the slightly useless but amiable Lowery begs Cory to kill him before he is transformed into a walking cactus.

Cory himself is pretty dour. The debt to James Bond is blatantly obvious. But it’s definitely the books’ Bond, with none of the suave sheen of the movie version. Cory coldly guns down Garvey, doesn’t hesitate to execute Lowery, and shows no patience with or sympathy for the men he’s co-opted for a mission so secret he hasn’t even bothered to tell his superiors about it. The only thing that stops him seeming totally inept is the Daleks are even inepter – announcing their galactic conquest plans over the tannoy at their base for all to hear.

Mission to the Unknown is a really odd episode. It definitely feels like the first episode of something – but the complete absence of the TARDIS crew, the bleakness of the ending and the general grim tone are quite a long distance from the type of programme Lambert has been making for the last year or so. All the humour Dennis Spooner introduced is gone. What’s left is a very unusual postscript to Lambert’s era – almost a backdoor pilot for a wholly different series.

Next episode: Temple of Secrets

Mission to the Unknown no longer exists. Not in any of its regenerations. This review is courtesy of the excellent animated reconstruction