In the 30th Century, the Terran Empire is planning to shut down the colony world of Solos. The Marshal (Paul Whitsun-Jones) and the Overlords rule the planet from the orbiting Skybase One. The Marshal is obsessed with eradicating the hideous mutants below. Some of the Solonion tribes on the surface oppose the occupation—Ky (Garrick Hagon) for one—and others, like Varan (James Mellior) collaborate. Varan and the Marshal have the administrator murdered before he can set about withdrawing the human occupation.
The Doctor and Jo are brought to Skybase One by the TARDIS, under the control of the Time-Lords. They have a message box which can only be opened by the intended recipient. That would be Ky, who has been framed for the administrator’s murder. Jo and Ky go down to the surface, which is poisonous to humans in the daylight. Jo survives with Ky’s help. Above, the Doctor learns that the occupiers are experimenting with rockets to terraform Solos, making it safe for humans but deadly for mutants, who are referred to as Mutts, and are rather repulsive creatures like giant scampi.
Varan has discovered the Marshal’s plan, but he is sought as an outlaw on Skybase. He and the Doctor flee to Solos and the Doctor learns that the Mutants are not hostile as described. Ky opens the box and finds ancient tablets written by the Old Ones. A human scientist, Sondergard (John Hollis), an expert in Solon anthropology living in the caves, helps mutants survive the poisonous gas. He tried to inform Earth Control about what was happening but was exiled to the caves. With his help, the Doctor learns that the mutant phase is a natural part of the Solonian 1000-year cycle.
Varan is becoming a mutant changeling himself. He keeps this a secret and launches an unsuccessful attack on Skybase. After informing the mutants that they are perfectly natural and not monstrous, the Doctor returns to Skybase and concludes that the Marshal is mad. The Earth government has dispatched an investigator. The Doctor is forced by the Marshal to decontaminate the damage the Marshal has done before the investigator arrives, because there are hostages. The investigator is given more lies by the Marshal and the Doctor is forced to back him up. But Jo and the other hostages escape and tell the investigator the truth. However, he is frightened by the mutants and decides the Marshal is right to wipe them out.
Ky continues his mutation but passes the deformed stage into a radiant angelic super-being stage capable of floating on air and passing through walls. The investigator sees the whole picture. Many on Skybase and on the surface remain to help the Solonions go through the next natural step. Jo and the Doctor slip away in the TARDIS, the Time-Lords’ mission complete.
The story was inspired by South African Apartheid. Sadly, the opening scene bears a strong resemblance to the opening of Monty Python’s Flying Circus, which made it difficult to take seriously. An episode of Star Trek the Next Generation featured a very similar transformation into a higher state of being. Salman Rushdie apparently made an oblique reference to The Mutants in the Satanic Verses. He does not mention it by name, and it is clear to me at least that he had mixed up several Doctor Who stories with similar, quite common, themes of Colonialism. Apartheid, and Xenophobia, but he does use the term Mutts. Whovians accused Rushdie of missing the point entirely and fans of Rushdie accused the Whovians of the same thing. In any event, The Satanic Verses gave Rushdie much bigger problems than a few Doctor Who fans with their noses out of joint.