The TARDIS, on the trail of an energy reading it seems unable to analyze, materializes in Alaska. Nyssa and the Fifth Doctor witness a plane fly away, and the TARDIS soon lands them in the same spot again, only 30 years later.
Investigating the readings, they're soon attacked by a monster and find shelter at an unusual museum being constructed by millionaire Shaun Brett as a monument to his late father. With the monsters roaming the snowy landscape outside and other dangers lurking inside the building, the Doctor and Nyssa try to make sense of it all together with Brett, his interior designer Monica Lewis, the misanthropic Inuit Gaborik, and the half-American, half-Inuit Tulung.
Tulung has been working for Brett all his life, ever since both of their fathers were in a mysterious accident thirty years ago. When Nyssa informs him that she saw a plane fly away during that time, Tulung latches on to her and lets himself get carried away by Inuit superstition and grief, hoping to find out what really happened to his father.
Meanwhile, the Doctor and Monica stumble on a collection of living dinosaur skeletons from 260 million years ago. The Doctor has a number of issues with that, not in the least because dinosaurs didn't yet exist 260 million years ago. Also, skeletons without any muscle tissue moving about autonomously violates just about every law of physics he can think of. The "Permians" don't care much about his fancy science, though, and immediately start eating the crew... and evolving towards a human form accordingly.
Brett eventually makes a Heroic Sacrifice to kill most of the beasties, the rest of the group burns down the house to wipe out the rest, and Monica and Tulung decide to build a new life together.
Land of the Tropes:
- Big Labyrinthine Building: Brett's museum, which has rooms constructed from bone, ice, wood and other materials representing the land, as well as a room filled with seawater, wildlife and transplanted Alaskan coastline.
- Body Horror: The presence of the Permians causes the local wildlife to twist, merge and deform, becoming grotesque hybrids striking out in fear and confusion. The Permians also eat people by stripping the flesh from their skeletons via energy field.
- Call-Back:
- The Doctor and Nyssa talk about recently leaving Tegan behind at Heathrow Airport.
- Nyssa tells Tulung about her world being destroyed. Tulung thinks she's being metaphorical.
- When looking at what they assume to be dinosaur bones, Nyssa remembers The Doctor telling her that they died out 65 million years ago. Later, The Doctor notes that most humans are aware of "the event" that killed off the dinosaurs, and Nyssa says that nobody is more familiar with it than they are.
- Crusty Caretaker: Gaborik.
- Deadpan Snarker: Being hunted down by monsters and facing imminent death only seems to give Monica more snark to draw upon.The Doctor: It's still coming after us.Monica: Of course it is! Wouldn't be a proper nightmare otherwise, would it?
- Disappeared Dad: The conflict between Brett and Tulung hinges on which of their fathers sacrificed himself to save the other many years ago; all we know is that they're both dead.
- Dug Too Deep: Gaborik (and eventually Brett and Tulung) thinks the Permians are the spirits of the dead risen up for vengeance for the destruction of the land by Brett's crew, but it's actually just this.
- Eldritch Abomination: The Permians, who predate the dinosaurs by 30 million years, according to the Doctor. The fact that they look essentially like animate fossils is actually the least bizarre thing about them.
- Evolutionary Levels
- Introduced Species Calamity: What is likely to occur if the Permians are allowed to roam free. Given that they were dangerous enough to consume 96 percent of life on Earth back in their own time period, they'll likely do just fine in the Alaskan wilderness; and since they absorb the traits of whatever they devour, they're only going to get more dangerous as they consume people and gain intelligence. The Doctor figures that if the Permians get loose in a city, within a few months they'll be intelligent enough to achieve space travel; and as if that wasn't bad enough, Nyssa suspects that if they ate a Time Lord like the Doctor, they might well learn how to operate the TARDIS, spreading their influence across the Time Vortex.
- Jerkass: Brett. He constantly baits Gaborik and Tulung into arguing with him, isn't that much nicer to the Doctor and Nyssa, and even planned to display Tulung's father's bones to the public upon opening the building, this last being what finally inspires Tulung to beat the crap out of him.
- Jerk with a Heart of Gold: Monica is abrasive and impatient, but she sympathizes with Tulung.
- Kill It with Fire: The Permians' only consistent weakness turns out to be fire, as it's the only "substance" too volatile for their energy field to allow them to adapt to.
- Sanity Slippage: An effect of the energy field generated by the Permians.
- Suspiciously Similar Substitute: Apart from the British accent, it's not hard to imagine most of Monica's dialogue being spoken by Tegan.
- Taking You with Me: Brett tries this on the Permians. It doesn't get all of them.
- You Are Who You Eat: The Permian leader starts to take on a more humanoid appearance after it eats Gaborik.
