On the surface, there are few less likely partnerships than the Twelfth Doctor – frequently dour, always dry, and usually thinking at right angles to most other people in the room – and Nardole, the sort-of Cyborg with both a cuddly persona and permission, when needed, to “kick [the Doctor’s] arse.”

Which just goes to show you should never blindly trust surfaces. There’s always something more going on beneath the surface, and usually it’s the more interesting stuff.

To class them as an ‘odd couple’ gets close to why they work together so well, but there’s also an element frequently overlooked. Most recent TV companions have been contemporary – or almost contemporary – with the viewers, the standard ‘ordinary humans having their horizons broadened by time, space, and the Doctor.’

In Nardole, what we have is something different. Something akin to the Doctor’s relationship with either of the Romanas. While the Doctor is always the Doctor, there’s a certain exhaling of the responsibility to talk at a level that would be understandable, and acceptable, to 21^st century humans. The result is a slightly sharper Doctor, able to swing a little more ego without coming across as patronising. And Nardole, in response, feels free to indulge in a degree more sarcasm with the Doctor than he otherwise might in the presence of 21^st century human colleagues.

This sharpness only serves to make their pairing even more comically enjoyable and spiky, and in The Nightmare Realm, by Jonathan Morris, those spikes are both delicious in their own right, and a very necessary counterpoint to a mish-mash world of…well…nightmares.

The scenario in and of itself will be familiar to any classic science-fiction fans. In fact, you might recognise the premise from a similarly titled classic American show. For Realm, think…Zone, and you’re in the right, creepily realistic, skewiff territory.

Arriving in suburban America, it’s barely a handful of heartbeats before the Doctor and Nardole find themselves locked in a bank vault to wait out a nuclear attack with one of the locals. While that in itself could make a solid episode of Doctor Who, that’s not the territory we’re in with The Nightmare Realm.

When the Doctor and Nardole find themselves mysteriously separated, reality begins to morph from one scenario to another – an invasion from outer space, Fifties B-movie style. A train journey where one by one, passengers are scooped up by mysterious alien tentacles – and then immediately forgotten by those left. A lynching in the Old West that gets significantly out of hand, and humans who melt into Something Altogether Different.

That’s a whirlwind tour of some of the highlights of the Nightmare Realm, and it doesn’t really do any of them justice. Nardole’s train journey and the potential lynching in particular will actually get your pulse racing with both familiarity and horror.

By the time you get to a sense of what’s really going on in The Nightmare Realm, there are some other genre high-notes hit, including a foot-stamping child-god who seems to be able to bend reality to his will, a creepy hospital room, and an army of Somethings from Somewhere Else trying to break in to either the Realm, or to a reality beyond the Realm.

And when you get to what feels like the end, there’s a twist that feels like you should have known it was coming, but which will still take you by surprise.

What you get in The Nightmare Realm then is a story that takes several sci-fi/horror TV tropes, especially those that made up the playbook of Fifties American writers, with some relatively new twists and an easy slide into the Doctor Who universe.

Added to that, there’s the spiky, sarcastic, and utterly joyous relationship dynamics between the Twelfth Doctor and Nardole. And between the child-god and what is, after all, a child, you also get both sides of the Twelfth Doctor’s personality – the challenger of those who claim supreme power in any situation, and the unlikely friend of the small and the scared.

If you were pleasantly surprised by the Twelfth Doctor in Listen on-screen, with his unorthodox approach to the scared Rupert Pink, and the joyful mad uncle positivity of his “Fear is a superpower” speech, you’ll love the Twelfth Doctor in The Nightmare Realm. While he always stands against the monsters, when it comes to understanding the fears that attract them, he’s both powerful and warm.

And when you finally find out what’s going on, his solution is complex in a way that means you have to keep hold of a couple of realities at once to follow it. It’s a version of a solution that, in itself, is a TV and movie trope, but it’s executed by Jonathan Morris with more-than-usual aplomb.

And while we’re talking about aplomb, it’s time to mention Dan Starkey, who reads this story. Best known as New Who’s favourite Sontaran, dating back to The Sontaran Stratagem, and most particularly standing out as Strax, the Sontaran butler, he’s extremely well known to Big Finish audio drama fans for the range of his vocal talents in a whole cornucopia of roles.

Here, he stretches to give us a reliable Twelfth Doctor which is not an out-and-out impersonation, but carries enough grace notes of the Capaldi incarnation to allow your brain to make the leap the rest of the way. And his Nardole, which feels closer to his natural voice, carries the squeaky cheekiness of Matt Lucas’ Series 10 portrayal. All the while, the ‘natural’ Starkey voice gives us an engaging, warm, never over-excited narration in between the dialogue, so The Nightmare Realm feels like a fast listen, despite covering a great deal of ground and delivering a handful of real thrills and chills.

The Nightmare Realm is a hugely enjoyable call back to a period in the Twelfth Doctor’s era that we never entirely saw on screen, but which was distinctly hinted at with Nardole going off on adventures of his own in time and space. Jonathan Morris gives us a shiver-down-the-spine adventure with the oddest couple to inhabit the Tardis since the Tenth Doctor and Donna Noble. Scary, funny, and with plenty of punch, it’s a great example of a Tardis team that could easily have run for seasons before they tackled the rehabilitation of Missy and the wonder that was Bill Potts.

Take a trip into The Nightmare Realm, and remind yourself of a great Tardis twosome that had plenty of legs. Tony Fyler