‘Playtime is over.’ After the knockabout Prisoner of the Judoon, this is more substantial and interesting. The premise is similar to Whatever Happened to Sarah Jane? in that it features another woman living in Sarah Jane’s house, and a crisis point in the past that has led to this moment. And there are some similarities in setting, too – the peeling Victoriana of the British seaside (here, Danemouth: a nice Agatha Christie reference).

This takes a different tack, though, by focusing not on the kids left behind in Sarah Jane’s absence, but on the one who stayed behind. Rani, it seems, has grown old and bitter from a lifetime of regret. In 2059 she’s the mad woman of Bannerman Road, the person Sarah Jane might, perhaps, have become left to her own devices and having never re-met the Doctor or adopted Luke.

Adam, presumably cast to look as similar to Luke as possible, prompts the older Rani to talk about the mistake that created this future. And it starts it an utterly convincing way, with Rani’s sense of wounded teenage pride and insecurity. She can’t help but compare herself to Maria, ‘the new Sarah Jane’, who’s assumed a First Mrs De Winter status in Rani’s mind – so when she walks in on her friends on a Zoom with Maria, and when Sarah Jane off-handedly dismisses her excitement about a freak storm, Rani decides to prove that if anyone’s going to be the new Sarah Jane, she is.

I think this works brilliantly: the teenage drama around the kind of minor annoyance that most adults would briefly brood over but then brush away. Anjli Mohindra is great, fulfilling most of the Sarah Jane role as she investigates the closed-up Pleasure Park and the weird, red-eyed zombies riding its attractions. These scenes are superbly creepy, like something from a darker tradition of children’s TV, and it’s a genius move to cast Sladen’s husband Brian Miller to play the strangely haunted fairground caretaker, 27 years after he played a similarly disturbed carny hiding something in Snakedance. Throughout, there’s a compellingly queasy atmosphere, of things being off-kilter, like Mr Smith having died years ago, and the red-faced demon, a refreshingly simple and effective bit of design, talking through mirrors to her servants.

Next Time: The Mad Woman in the Attic – Part Two