Praxeus’ foresight looks almost uncanny now, more than three months after it was first aired and who knows how long since it was filmed. The sixth episode of Doctor Who’s twelfth series, it sees the Doctor and her fam investigating an alien bacterium, the titular Praxeus, that feeds on microplastics, threatening to spread a deadly disease to every living thing on Earth.
The handling of its environmental message – viz., that the way we’ve contaminated our entire planet with a material that doesn’t break down poses dangers we may not be able to foresee – is a nice corrective to that of the heavy-handed and weirdly Cold War-reminiscent Orphan 55. Unlike the earlier episode’s oddly insubstantial warnings of mass migration and nuclear destruction, that of Praxeus is specific, actionable and educational without being didactic. And the environmental theme serves the story in an organic (hah) way. It’s interesting that Praxeus and the pandemic it threatens to cause is presented as a problem basically of our own making, in the light of recent comments from people like Inger Andersen, executive director of the UN Environment Programme, on the link between novel coronavirus and humanity’s destruction of wildlife habitats.
But Praxeus does less well on the details of epidemiology. Bizarrely, towards the end of the episode we find out that Praxeus is sentient (raising some moral questions about eradicating it that go unaddressed) and that it has built a kind of den at the bottom of the Indian ocean out of waste plastic after being released into the sea by an alien spacecraft.
Why? How? This isn’t how bacteria work! If Praxeus eats plastic, surely it would be breaking it down rather than building with it? And why does it need such a space anyway?
The Doctor and her friends work together to create an antidote to the disease caused by Praxeus and test it on Adam, a handy astronaut who’s been exposed to the bacterium. “You need a clinical trial, a human body, and now you’ve got one,” says Adam as he’s volunteering for this role.
Again: not how clinical trials work. You need thousands of people, not just one.
These are nitpicks, obviously, and generally I try to avoid such Watsonian critiques: they’re rarely helpful to looking at what a text is trying to do. But now, in the midst of the most significant health emergency the West has experienced since the Spanish flu…it’s important to get these things right. It’s important that people understand how disease works, and that writers don’t misuse technical terms like “clinical trial”. Misinformation is a killer.
In other areas, though, I felt Praxeus was a strong episode relative to the first half of the series, with a strong identity and a single unified theme. The relationship between Adam and his husband Jake is touchingly handled – the matter-of-fact inclusion of LGBT+ people is something this series is getting right. It’s not clear whether vloggers Gabriela and Jamila are a couple, but I certainly read them that way and I think the episode gives us the space to do so. Praxeus isn’t as good as its predecessor Fugitive of the Judoon, but it’s a solid entry in the series.