[WARNING: The Following Review Contains SPOILERS!]

Over its fifty-plus years on the telly, Doctor Who has never truly been a political show. At the very least, it would be fair to say that it rarely attempted direct commentary on current events.

Like most science fiction, the show examined serious issues through allegory and metaphor. And while episodes like Carnival of Monsters and The Curse of Peladon may not have made any deeper points beyond “Prejudice is bad”, they did still tackle the problems of xenophobia and racism with tact and nuance.

And then there’s crap like The Zygon Invasion, which addresses these issues with all the subtlety and grace of a wet fart during a church sermon. But what else could we expect from writer Peter Harness, who was also responsible for Kill The Moon?

For those of you fortunate enough to have forgotten or have never known in the first place, Kill The Moon was easily the worst episode of Series 8 and centered upon the idea that the Earth’s moon was a giant egg on the verge of hatching. The Doctor left the decision of what to do entirely in the hands of three women, saying he couldn’t get involved and that it was their choice, in what has to have been the most heavy-handed abortion metaphor in the history of fiction. The Zygon Invasion proves little better in handling the issues of immigration, terrorism and racism.

The episode opens with a quick bit of exposition for those viewers who might not have seen The Day of The Doctor. We’re told of The Zygons – a race of alien shape-shifters, who lost their home world and decided that Earth would a fine place to resettle. After two invasion attempts over 40 years – both thwarted by The Doctor and UNIT – an uneasy peace was reached.

It was agreed that 20 million Zygons would be allowed to live on Earth, in human form. Their identities would be held secret by UNIT, where two agents – a scientist named Osgood and the Zygon who copied her – would have sole access to the information. It was the perfect compromise, provided nothing happened to either twin. Unfortunately, one of the Osgoods was killed by The Master and the other fell into the hands of Zygon extremists, who wish to live on Earth openly without the need to hide their true forms. In order to deal with the impending invasion, The Doctor and his allies in UNIT will have to travel to both New Mexico in the USA and the non-existent but real-sounding country of Turmezistan.

Had this concept been handled with any degree of suggestion rather than overtly stating the writer’s points, it might have worked. Unfortunately, The Zygon Invasion has all the subtly of Brian Blessed leading a parade of naked belly-dancers and tap-dancing elephants, who are simultaneously trumpeting the greatest hits of Queen, in perfect harmony.

The Zygon rebels’ demands to not have to hide who they are mirror the complaints of French Muslims regarding their government demanding they abandon traditional religious garments in public. A bigoted American complains about Zygon immigrants talking strange and taking all the jobs and housing. There’s even a “NO BRITISH/NO DOGS” sign in New Mexico, just in case The Doctor explaining to the leader of UNIT that political extremists try to goad their enemies into extreme acts in order to polarize moderates fails to make the point that this is a VERY IMPORTANT STORY ABOUT HOW WE TREAT PEOPLE THAT ARE DIFFERENT FROM US. Not that we see any moderate Zygons working against their radical brethren or anyone apart from The Doctor arguing against mindless killing.

The preachy nature of this episode is bad enough. But what truly makes all this insufferable is how ineffectual our heroes are. The Doctor is totally helpless in dealing with a trigger-happy UNIT officer, who loudly talks about how she wishes they could just gas or bomb The Zygons into non-existence. The UNIT soldiers wander into an obvious trap after being confronted with images of their loved ones (i.e. disguised Zygons) begging for their lives. And Kate Lethbridge-Stewart (who has gone from being the scientist who turned UNIT into a scientific organization into a “bomb them all and let our White Christian God sort them out” military leader) seemingly goes off on a sojourn to New Mexico, alone, for no reason other than to establish a familiar scene for the American audience, who might otherwise be stunned to know that other countries have problems with illegal immigration!

The one thing that saves any of this is the actors treating the material with far more reverence than it deserves. Peter Capaldi is a wonder, playing The Doctor with an authority reminiscent of Jon Pertwee. Ingrid Oliver offers up some of the episode’s few fun moments as Osgood and Osgood. And Jenna Coleman’s performance is the one aspect of the show that improves upon a second viewing.

Alas, it isn’t enough. And the whole affair feels like a half-hearted remake of Doctor Who and The Silurians, reenacted by a group of small boys banging their action figures together. Usually a Doctor Who cliffhanger leaves the audience feeling excited. This one left them dreading next week.