A particularly strong episode that builds on the sinister weirdness of the first part, and confirms that beneath the veneer of happy order the colony is in thrall to monsters. There are clear overtones of Ian Stuart Black’s other first Doctor serial, The War Machines, in the mind control asserted over the colonists and, shockingly, Ben. The reveal of who’s really in charge is brilliant: a peeling back of layers as the benign publicity photo of the Controller dissolves to reveal a bewildered old man, who is in turn only a front for the Macra.

It’s a brilliant cliffhanger that twists what the audience might have been thinking. The crab creatures – glimpsed on the time scanner back in The Moonbase – Episode 4 – seem to be monsters patrolling the outskirts of the colony, terrifying Medok, and menacing Ben and Polly. Meanwhile, the Controller seems to be the one running the show, a Big Brother figure who uses Ola’s guard, hypnosis and perhaps even monsters to impose his will on the colonists. Only at the end do we realise that the Macra themselves are in charge. It’s as surprising a twist as discovering the Slyther was the mastermind behind the Dalek invasion of Earth.

The episode also utilises Michael Craze better than anything since The Power of the Daleks. Black remembers that Ben is a Royal Navy Seaman, and perhaps more susceptible to the voices of authority piped into his dreams than the rebellious Jamie. Ben’s use of military language – ‘on a charge’, ‘do my duty’ – certainly imply it. Craze rises to the material, giving the controlled Ben a frighteningly stern edge, and it all links back to the background theme of rising tension between him and Jamie. Had Craze left and Wills stayed on with Hines you can see how this tension could have played out.

Troughton continues to get good material to play with, now everyone seems to be on the same page with the Doctor’s characterisation. Here’ there’s a great scene of him faffing about with equipment in the Pilot’s office while the Pilot attempts to have a serious discussion, wrongfooting the authority figure. The scene includes a curious line of dialogue where the Pilot mentions, ‘Our ancestors came from the Earth planet like your young friends’ which suggests that either someone has revealed the Doctor isn’t human, or that the Macra have somehow discovered it.

Later, there’s a slightly dodgy moment where the Doctor creeps into Polly’s bedroom while she’s asleep – but it does give Troughton the opportunity for another second Doctor mission statement:

DOCTOR: Don’t just be obedient. Always make up your own mind.

Other observations:

• Did Medok invent the name Macra? No-one else mentions it until he starts ranting about them.
• The person doing the voiceover announcement on the Pilot’s tannoy is putting on a very strange accent
• The photograph of the Controller looks like an older version of Ben

Next episode: The Macra Terror – Episode 3