The Cybermen have arrived – and Kate Stewart could probably deal with them on their own. But they have an ally who’s Kate’s worst nightmare…

Ingrid Oliver has had multiple opportunities to play different versions of her UNIT character, Petronella Osgood. There was the Zygon version who debuted alongside her in The Day of the Doctor, and a second Zygon in the later story; and here she gets to play a partially Cyberconverted Osgood – one who is signed up (as far as we can tell) to the Cyber Ideal, and comes up with a great plan to help these latest Cybermen conquer the Earth. Guy Adams’ script gives Oliver ample scope to demonstrate her versatility in the role, and there’s something chilling about hearing her plot UNIT’s downfall.

That’s not to say that Adams doesn’t give the others plenty to do – we’re dealing with yet another different variant of Cybermen, which allows Nick Briggs to meld various versions of the voice together, particularly for the leader, and for once Josh’s Auton skeleton is a positive. There’s elements drawn from many different Cyber-stories (notably including Nightmare in Silver) which gives rise to a lovely scene in the UNIT armoury as Kate explains all the different ways that they can attack the creatures…

And then, just as things seem on the verge of utter disaster, there’s the sound of a TARDIS… but just whose?

Verdict: An extended runaround episode that works because of the unusual slants on the characters. 9/10

Paul Simpson