Can you imagine being asked back to a job you last did 28 years ago? In my case, I had a very brief career as a waiter at a smart restaurant back then. It involved two nights of serving vegetables using silver service, navigating around the warring, slightly sozzled husband and wife team who ran the joint, and being locked inside a walk-in refrigerator in a hazing ritual. Surprisingly, I wasn’t invited back for second weekend, and it would be even more surprising if I were to be asked back now.

Rona Munro’s career as a writer is staggeringly more accomplished than mine as a waiter, but it was still a surprise to hear that she was to become the first writer from 20th century Doctor Who to write for its 21st century regeneration. Actors, directors, costumiers and special effects staffers have all made the transition. But given how different the show is in focus, pace and structure, it’s always seemed like it would be a difficult leap for a writer to make. And 28 years is quite a gap; even in the classic series that gambit would never have been contemplated. It would be like Andrew Cartmel asking David Whitaker to write for season 27. (“David, we only have 14 episodes a season now. We can’t spend 15 minutes talking about the food machine!”)

Back when Munro was writing for the show, the Doctor was played by a brooding Scotsman, his assistant was a contemporary, streetwise girl who he was educating in the ways of the universe, the Master was undergoing a complete physical change and ratings were on the slide. Plus ça change. So it makes sense that her first story, Survival and her second, The Eaters of Light, share similar concerns.

Both are about creatures breaking through portals from other worlds to make murderous attacks on human prey. And both concern groups of teenagers struggling to understand and to deal with these alien incursions. 28 years ago, Munro demonstrated her ability to write lyrically and symbolically – about the need for a home, about sexual awakening and using intelligence to prove the old “survival of the fittest” maxim wrong. Here, I think she’s presenting a story of teens dealing with despair.

It centres on two characters, both baby-faced leaders of their tribes: Kar (Rebecca Benson), chief of the Picts and Lucius (Brian Vernel), leader of the remaining scraps of the Ninth Legion. Both have been floored by the slaughter of their comrades: Kar’s people were decimated by the Romans, Lucius’s legion by the lone Eater that Kar unleashed upon them. In the absence of older, wiser heads, they have been pushed into leadership roles, and both are plainly terrified.

In these characters, the allegorical side of the Eaters becomes clear; as creatures which feed on light but then suck that light away from others, they are stand-ins for depression. In a pair of consecutive scenes, our two young heroes are forced to confront the source of their troubles. Bill (Pearl Mackie) points out to Lucius that hiding out in a cave is not going to help anything, and that he needs to regroup and go on the offensive. Next, the Doctor (Peter Capaldi) tells Kar that it’s time to face up to her situation and fight back. “I’m afraid,” she admits. “But you’ve still got to face your beast anyway,” says the Doctor, never one for letting people off the hook.

Sufferers of mental illness will know the futility of being told, “just pull yourself together and feel better.” I don’t think that’s what’s going on here. What Bill and the Doctor are doing is helping Lucius and Kar recognise that although their problems are dauntingly huge, something needs to be done. Their problems can’t be sidestepped or hidden from, and that a personal decision to “face the beast” needs to be made. In this way, we see the turning points in both these young people’s stories. We see the moment where they get back up off the mat and decide to fight the force which is stealing their light. Good for them.

I’m not so sure about the ending though. Kar and Lucius are now able to speak to and understand each other, thanks to the Doctor’s powers of language translation. This enables them to sympathise with each other’s plight, in a kind of live example of the “sit down and talk” approach extolled at the end of The Zygon Inversion. They then decide to join forces and dive into a rejected title sequence to fight off the Eaters one by one. This will apparently go on until the end of time, because time moves faster inside the portal than out. But at a going rate of 70 years per defeat of each beast, and only a handful of brave fighters entering the fray, I can’t make the maths work.

Still, that’s not the most pressing problem. Surely once they’re cut off from Doctor they’ll lose their multilingual abilities. Difficult enough to coordinate a joint attack against a swirling pack of dimension jumping nasties at the best of times, let alone when you can’t understand what your newfound comrades are saying. But then again maybe “argh!” “ow!” and “gerroff, I’m having all the light sucked out of me” are universal.

The Picts also remember to take a couple of pipers down the cosmic plughole with them, which seems like an unnecessary luxury for such a dangerous mission. “Hey, band! Play that one I like, will ya? It’ll really help pass the time while I’m fighting for my life!” But that allows one of the episode’s more mystical elements – music emanating through the hillside – to make a kind-of sense. Except that again, isn’t that music still being played in a slower time stream than in the real world? Wouldn’t it be like listening to a record at super slow speed?

I shouldn’t be spoiling things. As the Doctor explains to Missy (Michelle Gomez, in an all-too-brief appearance), only the joyless can’t hear the music around them. It’s another metaphor for depression; Missy has to learn again to tune into that music which springs from the ordinary beauty of life. When she does, she’s moved to tears, but the sense is that she’s better off by going through the experience and coming out the other side. Again, those going through a mental illness journey of their own may sympathise.

Survival was about this too. Characters stuck in a dead-end suburb, battling with the slow, inescapable trudge of daily life. Characters who went through terrible ordeals, but came away from them invigorated and reconnected with the world around them. Characters who fought off ravenous beasts and were changed by the process. Munro has lost none of her ability to tell stories across multiple levels and to use fantasy to reflect on our own reality. Let’s hope it’s not 28 years before we hear from her again.

LINK TO Victory of the Daleks: aliens interfering in historical battles.

NEXT TIME… it’s back to the dark places of the inside for Kinda.