Every year a race who call themselves the Gonds select their two best students to become the “companions” of the Krotons, which is considered a great honor. Outside the Gonds’ city, the Doctor, Zoe, and Jamie arrive, seeing a desolate world with twin suns. Despite his companions’ reluctance, the Doctor insists they set out to explore. They stumble across a Gond being disintegrated in a machine. Next they come across a group of Gonds, where one, Thara, is struggling to stop his lover Vana from being sent to the Krotons. The Doctor recognizes the door as resembling the one that led into the deadly machine. Unable to stop Vana from going to the door, they and Thara rush out into what the Gonds call “the wastleland” to try to find her. They save Vana from being destroyed, but she’s in a catatonic state. After taking Vana’s unconscious form to the home of Thara’s father, a Gond leader named Silras, he explained to the Doctor and the companions that the custom of submitting two of their smartest young people to the Krotons started a thousand years ago, when according to legend the Krotons came from the sky and were attacked by the Gonds. The war ended when the Krotons brought down a poison rain that devastated most of the planet. The Gonds consider the Krotons to be their benefactors, who have set up machines that see to all of their needs and education, but no one has seen a Kroton in centuries. However, after explanation time the Doctor and Silras realize too late that Thara and a group of rebellious students have started smashing the Krotons’ machines in the city’s main hall. The Doctor arrives on the scene, only to be terrorized by, well, a probe (there’s no way to make that sentence sound less than filthy).
Zoe tests herself on one of the machines and in a trance tells the Doctor that she knows the Krotons are “very pleased” with her. The Doctor is dismayed when the Gonds want to have Zoe sent to them and takes the test for himself to make sure he can accompany Zoe. After being assured by Silras that his people will “always remember him,” the Doctor and Zoe go to meet the Krotons. Inside the Krotons’ lair, the Dynatrope, Zoe and the Doctor find themselves having their mental energy siphoned off. Thanks to not being subjected to a lifetime of brainwashing like the Gonds, however, the Doctor and Zoe are able to rush through the Dynatrope, taking some liquid to analyze later, and escape. Jamie breaks in after them, only to wind up the Krotons’ latest test subject. Under the Krotons’ mental conditioning, Jamie blurts out about the TARDIS.
Jamie learns that there are only two Krotons. They are an immortal crystaline species who have been trying to collect enough mental energy into the Dynatrope, which is their ship. In a run-in with one of the Krotons in the wasteland, the Doctor figures out that the Krotons cannot see in the light and rely on directions from their partner inside the Dynatrope. Meanwhile a power struggle among the Gonds ends with the ambitious Eelek coming to power. Eelek agrees to the Krotons’ demands that they hand over the “high brains”, meaning the Doctor and Zoe. Forced into the Dynatrope by Eelek and his supporters, the Krotons demand that the Doctor and Zoe use their mental energy to help fuel and pilot the Dynatrope back to the Kroton homeworld. Unfortunately for the Krotons, the Doctor was able to analyze a way to contaminate the Krotons’ energy supply with sulfuric acid and Zoe manages to do so while the Krotons are explaining why they need some “high brains.” Thara and Vana use sulfuric acid to destroy the entire Dynatrope, while the Doctor, Jamie, and Zoe slip away.
“Yes, well, Zoe is something of a genius. It can be very irritating at times.”
It’s when the Second Doctor says “Oh my giddy aunt”, which still gets erroneously remembered as his catchphrase.
This is the first time an episode was written by Robert Holmes, who would go on to easily become the most famous scriptwriter who ever worked on the show besides Douglas Adams. Ironically enough, Holmes’ relationship with “Doctor Who” started as something of an accident. “The Krotons” was actually a heavily reworked idea he had for his own serial that he pitched to the BBC and got rejected. Someone suggested he take the idea to the producers of “Doctor Who”, who rejected it again—until the script was found years later when an assistant script editor was clearing the script backlog. And even then it didn’t get produced until it was needed for an emergency replacement for an episode that got axed!
It’s the debut of “Who” legend Robert Holmes as the scriptwriter and it’s…okay.
From what I’ve read, the script got some major overhauling from whatever Holmes originally envisioned into a “Doctor Who” episode, but you can still see the scars from that surgery. There’s a complicated political subplot with the Gonds that suggests something deeper, but it all feels really compressed (especially when a couple of characters key to the plot seem to pop up out of nowhere) and ends up just being why the Doctor and Zoe get stuck on the Dynatrope. It has the effect of making these episodes, a short series by the standards of this era of the show, feel like they’re treading air.
A real missed opportunity was the monsters du jour, the titular Krotons themselves, who really bring to mind the giant Servo from MST3K. I get this was an emergency replacement so we couldn’t expect too much, but, given how many details the episode gives about the Krotons being truly alien, they’re really a missed opportunity. Instead of the sheer weirdness of the Animus from “The Web Planet,” we just get what comes across as yet another second-rate replacement for the Daleks.
For all that, there is a certain weight to the story that makes it believe that this still came from one of the best writers to work on the show. The setting has a little more depth than what we usually see, even if the characters can’t agree if the Krotons had been around for a thousand years or thousands of years. Appropriately enough for Holmes who would become famous for hammering in a message into his episodes, there does seem to be an interesting theme in here, about a society that literally sacrifices its brightest for the self-interest of a couple of war-loving goons it wrongly sees as its benefactors. I bet it’s no accident that you can easily read all of that into the Doctor’s struggle against two bulky cousins of Tom Servo.