This has the whiff of those turn of the 70s dramas (probably featuring Glyn Houston) where everyone is very serious, staring urgently at monitors, barking down the phone and saying things like, ‘Damn it, Marjorie!’ rather than having any actual incident. This actually makes it quite novel for Doctor Who, which even in the hinterland of the Pertwee years rarely featured anything quite so ordinary, but it’s hard to see much to entertain the kids here.

What fun there is comes from Tom Baker and Elisabeth Sladen enjoying their last few hours together. Sladen’s childlike repetition of ‘Eldrad must live’ is quite creepy, reducing Sarah to an infantile puppet. The Doctor seems to be quite moved by it – when Houston bursts into the infirmary all guns blazing, Baker plays it very calmly, softening his voice and gently talking Professor Watson round. Later, in a moment that RTD seems to have lifted for the tenth Doctor’s final scenes with Donna, the Doctor gently puts Sarah Jane into a trance with fingertips to the temples to try to find out what exactly has got into her.

He has to do this because halfway through the story, a bit of creeping hand action aside, there isn’t a monster (blank-faced technicians waving Eldrad’s ring about don’t count), and the peril is still very ill defined. It’s true that the 1970s audience could be counted on to clock the horror of impending nuclear meltdown (and it’s reinforced by Watson’s sweet phone call to his wife), but the cast are in and out of the reactor like it’s a public convenience. Having two separate but almost identical meltdown threats that open and close the episode is a good indication of how little progress this story is making. Eldrad must get on with it.

Next episode: The Hand of Fear – Part Three