A Zero Room sum game – Why I love Castrovalva


Image Credit: Gioachino di Monaco (CC BY-SA 3.0, Wikimedia Commons)

Image Description: The real city of Castrovalva

By Evan Jones

I will be the first to admit that Castrovalva is not an unloved Doctor Who story, but it certainly is a rather underappreciated one in my eyes. It perhaps has some of the most tepid and lukewarm divisiveness among fandom, ranking 121 out of 241 stories in Doctor Who Magazine’s 2014 poll, which apparently makes it the median Doctor Who story – not exactly terrible, but not exceptional either. However, some reviewers really have it in for Castrovalva. For example, Christopher Bahn’s review of the serial for The AV Club describes it as having “an unclear and often dull storyline, poor costumes, and atrocious acting”. Whilst nowhere near as harsh, I posted the following tweet shortly after first watching it five years ago: “Like Logopolis, I can’t help but love the use of mathematical themes but it was a weaker yet enjoyable story. 7/10.” It would seem lots of very good things get review scores of seven out of ten.

However, upon revisiting this serial in January 2020, I was surprised to find that I had changed my mind, and quite dramatically too. It was almost like opening a Chinese puzzle box, or, if we want to keep it distinctly 1980s, solving a rather fiendish Rubik’s Cube; suddenly all of the pieces had clicked into just the right place. Now, I am not only keen to suggest, but actually contend that it is one of the most accomplished serials in the show’s original twenty six year run, which I admit is a much stronger statement than necessary here! I’ll limit myself to three good reasons why I rather like this story.

First off, I love the story’s motif of recursion, which is when a structure or process is defined in terms of itself. This itself is a comment on the unfolding nature of Doctor Who, with each iteration of the show changing and responding to what came before, developing into something more complex. It’s unsurprising that its writer, Christopher H. Bidmead, employed the theme in a Doctor Who story given his fascination with computers and how they work. Both computer hardware, and software, benefit from using simple recursive structures to develop increasingly sophisticated and complex systems;  the very idea that underlies the simulated world of Castrovalva. The plot itself reflects this idea with the Doctor’s arch nemesis, the Master, laying trap within trap for him to find.

The TARDIS is also reinvented under Bidmead as a highly advanced computer. Now we learn the TARDIS has data banks full of information, that rooms can be stored and deleted like blocks of memory, and that the internal architecture of the rooms can be reconfigured. The TARDIS is shown as being a disorientating and labyrinthine structure that one must navigate and as the Doctor stumbles his way towards the Zero Room at its centre, he also navigates the layers within himself. We see this through the unravelling of the scarf worn by his previous incarnation and the recalling of memories from those further back still. The Doctor’s identity is itself a recursive process, growing in infinitely complex ways from a distant and shrouded past; we will probably never know where it truly started (you may need to turn a blind eye towards The Timeless Children at this point), but we will always see where the Doctor goes.

I also love the use of Escher’s artwork in this particular serial. The title itself takes its name from a 1930 lithograph by the artist of an Italian village on a hillside, but Escher is arguably best known for his artwork of impossible structures and optical illusions, featuring staircases that never end, waterfalls that flow in perpetual motion, and hands that somehow draw each other into existence. It is not just the title but these philosophical musings that are used to create the world of Castrovalva, so naturally the set and costume designers also drew inspiration from his works. Even Fiona Cumming, keen to bring the logical trappings of Escher’s art to the screen, directs her scenes in such a way that they break the conventional ‘grammar’ of television drama, with characters exiting and entering the screen from the same side between shots. You can even spot one scene in particular where Nyssa looks down on the village square, only to find that when she goes out the door, she’s somehow on the ground floor already – no stairs required! How many other shows get the opportunity to create and explore these fantastical and impossible worlds?

Lastly, I love the story’s broader philosophical statements. Here the new incarnation of the Doctor is on his own philosophical journey, one of self-discovery. Bidmead knew whilst writing this that it would be filmed in the middle of Peter Davison’s first run of stories and that Davison still had to settle on how he would play the part. So somewhat boldly, he decides that, rather than use the previously established excuse of post-generation madness, he will instead play into Davison’s anxiety and uncertainty about the part in the plotting of his story; something that works magnificently. Davison is given the narrative space to re-adjust his performance as needed, allowing the story and the character to be wonderfully and beautifully intertwined. He is thematically present even whilst he is physically absent.

Castrovalva itself is also profoundly philosophical, presenting itself as the ideal civilised society before later being revealed as a simulated reality. Mathematics is a subject that can be characterised as the search for truth and the very basis of mathematics is an area that blurs the line between itself and philosophy. Here it is mathematics that reveals the world is a simulation, through the increasing realisation of the world’s recursive nature, culminating in the glorious third part cliffhanger: “We’re caught in a space-time trap!” What else would you expect to happen to an adventurer in space and time? 

This aspect draws a parallel with the Capaldi-era episode Extremis, where the Doctor, Bill and Nardole find themselves in a simulated world, which itself is also revealed through a piece of mathematics – the pseudo-random nature of random number generators within computers. We still see the Doctor defy the creators of the simulation by using the world against them and this is also mirrored in Castrovalva by the self-sacrifice of Shardovan in defiance of the Master who created him. I like to think that both the Doctor and Shardovan escape from Castrovalva in search of the truth about themselves, even if one of them does so by swinging from a chandelier into the Master’s hadron web. How else will we truly find the limits of who we are? The ending of Castrovalva sees the Doctor at last come to terms with who is now. No longer struggling with who he once was, or worrying about who he is going to be, he is content with his present self, and he is all the more enlightened because of it. As the Doctor so neatly puts it, “Whoever I feel like, it’s absolutely splendid.”

The double issue of Tides 45/46 is, at time of publication, available to buy through this link

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