The show’s 200th episode passes by without fanfare as the story meanders along pleasantly enough, throwing in some good creepy moments. Sadly, it also includes some really odd acting choices and script oddities that are inadvertently perplexing, and tend to detract from any sense of mounting tension.

Director Hugh David has assembled a strong cast – but they struggle to do much with a script that is comfortable with the domestic soap opera aspects of the story, but flails about like the seaweed monster when it needs to create credible workplace drama. Victor Maddern isn’t a bad actor, but as Robson he starts off as a man on the verge of a nervous breakdown, and only gets more hysterical. In this episode he seems utterly unhinged, yelling at everyone, throwing out wild accusations and raging that, ‘I’m in charge here!’ I’m not sure about the deep, but there’s definitely fury in the board room.

We could really have done with more context for Robson’s breakdown – Van Lutyens and Harris talk about him cracking up under the pressure, but a couple of video calls with the fearsome-sounding Megan Jones, who’s apparently piling on the pressure, might have helped. As it is, it just looks like she’s stuck a madman in charge of this project.

Possibly by way of contrast, Troughton plays the Doctor as more laid back as he’s ever been – practically horizontal, in fact. He sounds like he’s been on a different kind of weed through the episode, and even stumbles over his lines when he tries to assert some authority in the control room. I wonder if he had a cold, because this doesn’t feel like his normal performance at all.

I enjoy the bits of the script that add some reality to the relationships in the base – Robson’s nasty suggestion that Maggie is suffering from a hangover implies a whole colony of bored and neglected women whose husbands are working out on the rigs, leaving them in their garishly-wallpapered residential quarters with nothing but a bottle of gin for company. And Harris’ concern for his wife feels very true.

I also liked the picture of the Weed Creature in a book of old sea legends, which gives almost a folk horror aspect to the story, especially as it starts to possess Maggie with weed fronds poking from her sleeves – ultimately, and hauntingly, causing her to walk out into the waves as it claims her. But writer Victor Pemberton stumbles when he moves away from the vague ‘thing from the sea’ aspects of the creature into more sci-fi specifics: the idea of scientists being surprised that seaweed is a living organism is baffling, and it feels like a throwback to the script’s origin as The Slide, a story of the earth and mud coming to life.

Pemberton’s treatment of Victoria is a bit better than some more recent writers. Perhaps as he script edited her first adventure, he recalls more about her character and background. There’s a lovely scene of her assisting the Doctor in his lab as she may have her father. And her sudden upset about being scared all the time makes more sense given she’s just witnessed monsters bursting into a domestic setting in the same way the Daleks invaded her father’s home. She starts to have a life discussion with the Doctor which is left unresolved, but which neatly points towards things to come.

Next episode: Fury from the Deep – Episode 4