Part of the joy of early Doctor Who episodes stems from the fact that when you look past the wobbly sets and laughable special effects, you see not only a lot of heart being poured into these stories, but a lot of deep ideas as well, with literary references flying around everywhere you look (something that was definitely lost by the time we came around to the Sylvester McCoy era). Without the freedom of budgets, the show’s creators had to use their brains instead, and as such, there are lot of joys to be found in the Doctor’s fifth-ever adventure, The Keys of Marinus.

Things start off intriguingly enough: the Doctor (William Hartnell) and his usual bevy of companions (granddaughter Susan, her teachers Barbara and Ian) land on the planet of Marinus on a small island, the beach of which is made of glass and the waters of which are made of acid. Upon entering a tower (with its several spinning false walls), the TARDIS crew meet Arbitan (George Colouris), who is the keeper of The Conscious of Marinus. 

The concept is fascinating: the Conscious—a bulbous supercomputer—was created to make things like trials become completely non-existent. The Conscious was essentially programmed with enough moral fortitude to determine what was good and what was bad so that people didn’t have to, and before long, the society of Marinus became completely non-violent because of the computer. However, a race of creatures called the Voord were unaffected by the Conscious, so when they began attacking citizens of Marinus, these defenseless lifeforms couldn’t do anything—they had been stripped of their violent tendencies, afterall. Now, the Voord wish to control the Conscious so that they can rule the entire planet.

Of course, being a Doctor Who episode, Arbitan has crafted several microkeys that make the Conscious work, and has scattered them all over the planet for safety reasons. As soon as the Doctor and co. discover this, Arbitan implores them to find the keys before the Voord do, sending them all across the planet, and… well, you can guess how things unfold from there. (The same exact conceit was used for a later series of Tom Baker adventures, The Key to Time).

Between the four “stories” that make up this six episode arc, we’re treated to exotic Roman-themed fantasy lands (“The Velvet Web”), jungles filled with trap-filled temples and crazed plants (“The Screaming Jungle”), deceiving hunters lost in a wintery landscape (“The Snows of Terror”), and—in the most delightful twist of all—a full-blown courtroom murder mystery (“Sentence of Death”). The concepts and ideas in each episode are almost completely unrelated to the other ones around it, and even with a few I-can’t-believe-they-did-that moments (apparently, hugging walls in plain sight makes you invisible—that or peripheral vision wasn’t invented until after 1964), the episodes remain thematically strong and character-driven like the best Who episodes tend to be. 

Of all of these fun little detours, “The Velvet Web” had the most interesting story from a purely conceptual standpoint: the Doctor and co.—now ordained key-hunters—find themselves in a world wherein everyone’s wish is seemingly granted without hesitation .The place is called Morphotron and its inhabitants are very, very happy.  If someone wants a fancy dress, they get it. If the Doctor wants a laboratory set up wherein he can conduct ingenious experiments, it’s done within a day’s time. Everything seems wonderful in the land of Morphotron—at least until Barbara discovers that everything is not as it seems. 

In fact, a group of evil brians (just go with it) have been putting everyone under a sort of hallucinatory hypnosis wherein it merely appears that people are getting what they want—the truth is far less gaudy. The Doctor may “see” his laboratory all shiny and new, but in real life, the room that it’s house in is empty except for an old wooden table, his beaker turning out to be a dusty mug. With each passing second, everyone falls deeper and deeper into this elaborate fantasy setup, but Barbara is determined to set her friends free. 

Although the allusion isn’t deliberate, this very much harkens back to L. Frank Baum’s idea of what the Emerald City was in The Wizard of Oz: the emerald structures were simply so blinding that everyone visiting (much less living in) the city had to wear special glasses to protect themselves at all times, as even the faintest hint of emerald light could cause serious, serious injury. The truth, however, was much different: the Emerald City was in fact a bunch of regular buildings that were dilapidated and falling apart, the “special glasses” designed to actually project the image of an emerald-encrusted landscape when, in fact, nothing was.

This illusion of grandeur instilled a senee of wonderment in all the city’s inhabitants, gaining the loyalty of the city’s people through sheer indoctrination, despite the fact that things were worse than ever—much like Morphotron (although the Who episode resolves in quite a different fashion than Baum’s book). Much can be read about how Morphotron is about controlling class systems through promises of prosperity (and, despite the budget, there are some really neat effects used to convey Barbara’s disillusionment here), and the point—which is not as heavy-handed as you’d be lead to believe—is well-made. 

Although “The Screaming Jungle” and “The Snows of Terror” both have their own over-the-top moments (and classic shoestring-construction moments, like the “spike ceiling” in “Jungle” and the “frozen” ice warrior statues in “Snows”), it’s “Sentence of Death” that really launches Marinus to new heights. Here, Ian is transported into the robust city of Millennius wherein he discovers the last micro key being kept inside a museum with tight security. He needs to take the microkey for himself in order for the Doctor to complete Arbitan’s quest, but someone else has the same idea, and it’s not long before Ian is knocked conscious by a mysterious thief and is immediately framed for the murder of one of the museum guards. Soon, Ian is forced through a legal system where everyone truly is guilty until proven innocent (as that’s the law in Millennius). 

What follows is a twisty, exciting ride through an alien legal system, the Doctor having to designate himself as Ian’s legal council as every guard and government agent is interrogated and questioned (the Doctor-as-lawyer template works quite well, even doing wonders for Colin Baker later on in Trail of a Time Lord). It’s not long before villainous double-crosses take place, suspects turn into murder victims, and Susan herself is kidnapped as a bargaining chip in this nervy courtroom thriller. 

In fact, the drama gets so heated (at one point the crew receives an ominous call wherein they’re warned that if they reveal the location of the microkey in open court, someone will die right then and there), that you wind up getting sucked into that and not really caring about the ending of the whole Marinus thing anyways (and the ending, admittedly, is a bit rushed). This isn’t to discount the ominous betrayal in “Snows of Terror” or the scientific detective story that drives the climax of “The Screaming Jungle”, but between “The Velvet Web” and “Sentence of Death”, it’s hard to find more engaging Hartnell adventures. 

What’s most curious about this particular set, however, is one of the featurettes: “The Sets of Marinus”. In it, designer Raymond Cusick (who’s also on the commentary track) simply seems bitter and disgusted with his own work on the show, the whole thing ending on whether or not he felt proud about any of his work on Marinus, to which he answers, quite dourly, “no”.  It’s an odd, surprisingly dour extra, and even though it has some interesting behind-the-scenes tidbits, its inclusion is still a bit of a mystery.

Yet even that doesn’t detract from the wonderfully overambitious Marinus. In it, one will find deep meditations on the meanings of justice, morality, trust, and class systems—wobbly sets and peripheral vision be damned.