Let’s say you’re a wounded alien warlord stranded in an ersatz Soviet training camp in Scotland in 1980. (I know. That old story, right?) You need to send a message to your homeys to come and pick you up and heal you. So you can set up a rescue beacon. Or call a space Uber or something right?

Sure, you could do that… if you’re from Planet Mundane! But the Fisher King (Neil Fingleton, and the voice of Peter Serafinowicz) is not. Nowhere near. No, he prefers a more ingenious method. He scratches some alien symbols on the wall of a spaceship. These symbols have the power to embed themselves in your subconscious without you knowing or wanting them to. Y’know, like dialogue by Eric Saward.

The symbols are actually the directions needed to find the Fisher King, but this is no simple set of galactic coordinates. Nothing so helpful. These directions are in the form of a particularly oblique brain teaser. The instructions in question are “the darkness, the sword, the foresaken, the temple,” which is a bit like giving the ambulance a cryptic crossword puzzle to solve in order to find your house so they can stop you from dying.

So anyway, the directions you so desperately need to get to your would-be rescuers are lying dormant in the minds of unsuspecting graffiti readers. To transmit those directions, the folks with the quizzical message embedded in their brains, have to die. Then they (somehow) turn into spectral beings with murderous intent, all the better to bolster their numbers and boost the signal and get His Majesty of the Fishers home and hosed.

Who said writer Toby Whithouse likes to over complicate his underlying concepts? Oh that’s right, it was me. Here. And here.

Now let’s say you’re a caustic old Time Lord whose accent makes him sound right at home in 1980s Scotland (Peter Capaldi). You need to find out how this whole “ghosts in the Drum” thing started, so you travel back in time to before the lake was flooded.

(The Drum being the name of the underwater base which is housing all the action. Its main feature is lots of lovely corridors to run down. The lake it’s submerged in never gets a name, but I like to think of it as Lake Siege. Then it could literally be a base under siege. Well, I’d laugh.)

Anyway, you travel back in time to before the lake was flooded.  There you discover the Fisher King and work out his nefarious, if overcomplicated, scheme. Easy enough to stop that – just blow up the dam wall and drown the sucker.

Thing is, you need to send a message to yourself from the future to spur you into action. So probably the easiest thing to do is write yourself a note. Maybe on the side of the spaceship, seeing as that’s where everyone goes for some light reading.

Doctor. The thing causing all the ghosts is a big alien nasty called the Fisher King and Clara’s next on his hit list. Go back in time and blow up the dam. Record the roar of the Fisher King as you do, so you can trap the ghosts in the Faraday cage. Also, never wear that jumper with the holes in it again, you look a right berk. Love, the Doctor.

Simple, right? But we don’t do “simple” around here, oh no. So what you do is write a piece of sentient software (in the TARDIS, I suppose) which creates a hologram (somehow. Not sure how it gets projected) that can walk and talk around everyone else. It will look like one of the ghosts and activate at a pre-determined time once you’ve left the base. You know, just to freak everyone out.

Then your Doctor Ghost will start to mouth a sequence of names, in order of who’s going to die (again, it might be simpler for him to just say what’s going on, but a silent list of names is much more complex). Including Clara in this list will be the catalyst for you to act, but if you throw in one of the crew members’ names before hers, that crew member will needlessly die, so watch out for that.

(To make matter worse, that crew member is the glorious Alice O’Donnell (Morven Christie), one half of my new favourite twin set of would-be companions, O’Donnell and Bennett (Arsher Ali). She’s full of fangirl enthusiasm, he’s all caution mixed with scientific curiosity. Plus both have practical skills from working in a military base and they have unresolved sexual tension between them. Perfect! When they board the TARDIS for our quick trip back to 1980, they look absolutely right beside Capaldi’s spiky Doctor. They could have been the Barbara and Ian of our times. Ah well.)

So your holographic ghost will be mouthing names spookily but also wandering about the place. In this way, your ghost can also pointlessly menace the remaining crew members by, say, helpfully letting all the ghosts out of the Faraday cage and letting them continue their killing spree. This isn’t strictly necessary but it extends the terrifying ordeal a bit longer for everyone and keep them on their toes.

I shouldn’t moan. I genuinely like this story with its creepy setting and its likable characters. I’d say it’s Whithouse’s best work for the show, though there’s a lot to be said for the old adage, “keep it simple.”

But why characters who want to communicate with their future selves insist on leaving cryptic messages all over the place instead of just writing a note always baffles me. I call it the Bad Wolf paradox and it’s far more prevalent than the “bootstrap paradox.” I wish the Doctor would spend a pre-credits sequence explaining that one.

ADVENTURES IN SUBTITLING: when Prentis suggests the Doctor could “oppress him” the subtitles suggest “appraise him” like he’s on Antiques Roadshow.

LINK TO The Greatest Show in the Galaxy: each feature avatars of Doctor Who fans – O’Donnell and the Whizz Kid.

NEXT TIME… You stupid butcher! It’s time to embark on The Crusade.