‘Of course, the Master.’ It’s not just the Master who’s back: weak endings were a hallmark of the Hinchcliffe years, and make an unwelcome return here. The Doctor’s underwhelmed reaction to coming face to face with his greatest frenemy is par for the course in an episode that fizzles out.

There’s some business with the Source Manipulator plans that go nowhere, and the Five Rings of the Consuls seem to be briefly important until they aren’t. Adric and Nyssa build a thing that overloads the Source and blows up the Melkur just as things start to look bleak. When he’s not zapping guards with the ion bonder, the Doctor spends most of the episode standing about watching events unfold – which, after Warriors’ Gate also depended on him doing nothing, is an unfortunate bit of sequencing. Unless that’s deliberate, to reduce the Doctor’s perceived “invulnerability” and marginalise Baker in readiness for the coming change.

There’s still a lot of details to enjoy in this, many of them related to the Master. His bitter ex description of the Doctor as ‘an unhappy man’ is great, and Geoffrey Beever’s performance, sniffing around the Doctor like a hungry rat, fingering his hair and practically salivating over the prospect of getting his manky hands on that body. The coda is great too: the Dcotor cheerfully warning Tremas that his ‘luck’s just run out’; a clock reading four to midnight; Tremas possessed by the Master – the unfinished business is all good set-up.

So on balance, I think this is a success, albeit one that’s held back from the top tier by its baggy second half and the lack of a genuinely punchy confrontation between the Master and Doctor. It’s oddly similar to the plot of the Star Wars prequels, as a wicked, cowled figure plays on love to turn a liberal democracy into a dictatorship. It looks great, the stylised dialogue works, it’s just an episode too long.

Next episode: Logopolis