The very title of the Doctor Who episode “Underworld” hints at its intersection with religion. But while the “underworld” in question turns out to be a world of tunnels with no access to the sky, the episode nevertheless more than lives up to the expectation that it will provide interesting terrain for exploring religion. Although numerous details regarding the nature of that planetoid (not to mention many other things in the episode) are at best implausible, the exploration of religion and mythology is interesting – as is the tidbit of backstory about the time lords that it provides.

The story begins with the Doctor, Leela and K-9 reaching the edge of the cosmos in the TARDIS. There, they encounter a ship whose crew are Minyans from Minyos. Minyos was a world where the Gallifreyans intervened to help the then primitive people, and came to be viewed as gods. Eventually the Minyans kicked their gods out, and the Gallifreyans as a result adopted their policy of non-interference – a sort of time lord “prime directive.”

This Minyan ship turns out to be on a quest to find the race bank, a genetic store of their people’s identity that will allow them to settle a new homeworld, their original home planet having been destroyed.

The Minyans have technology that allows them to regenerate a seemingly endless number of times. They have been on their quest for a hundred thousand years, and in discussion of this, it is mentioned that while they have been able to regenerate their bodies and minds, their spirits are at the point of degrading.

At several points in the story, the patterning of the episode on the Greek myth of the Golden Fleece is hinted at. Indeed, even the term Minyans might well have been intentionally chosen by the authors, since it is a term for an ancient people who are supposed to have lived in the Aegean region in prehistoric times.

The Doctor supposedly encountered Jason, making that myth a historical fact in the show’s world. As the Doctor actually says at one point in the episode, “Myths often have a grain of truth in them, if you know where to look.”

But the idea of myth as prototypical, and history as cyclical, is also explored – particularly at the very end, when the Doctor ponders whether myths are not just stories about the past, but also prophecies about the future.

All this while the gods of the Minyans are in fact simply technologically advanced aliens, the time lords.

The path to the race bank is likened to a tree, allowing for an even closer connecting of the Greek myth with the story. “The tree at the end of the world is always guarded by dragons,” the Doctor quips.

Meanwhile, this episode, like “The Face of Evil,” features a megalomaniacal computer that, in this case, explicitly claims to be the only god, self-created and all-powerful. And so this provides an opportunity to talk about Gnosticism, among other topics. That computer, known as “The Oracle,” somewhat ironically ends up at cross purposes with the Minyan crew, since it was presumably programmed to protect the race bank.

This episode is often viewed negatively in terms of the plot and special effects. But in terms of the opportunity it provides to explore the intersection of religion and Doctor Who, it is one of the best Doctor Who episodes there is.