The one with evil Judge Dredd.
The Doctor returns to Peladon, some fifty years after his first visit. King Peladon's daughter, Queen Thalira, is now in charge, advised by the inevitable Evil Chancellor, who promptly arrests the Doctor and Sarah Jane. Alpha Centauri, the squeaky-voiced octopoid from the last story, is now the Federation ambassador to Peladon, and clears the Doctor's name.
A spectral image of Aggeddor (the titular Monster, a god of Peladon) has been blamed for a number of deaths among the Trisilicate miners. The Doctor discovers that the spectral image is the work of a human engineer, Eckersley, who is working in cahoots with some renegade Ice Warriors to seize the Trisilicate deposits for a rival power bloc, Galaxy 5.
The Ice Warrior leader, Azaxyr, leads an attack on the throne room, but is killed along with his comrades when the Doctor turns Eckersley's heat ray on them. Eckersley takes the queen hostage, but the Doctor and the real Aggeddor hunt him down. Eckersley is killed, but so is Aggeddor.
Galaxy 5 surrenders to the Federation and the Queen offers the Doctor the chancellorship, but the Doctor suggests Gebek, the miners' leader.
"Glorious Goodwood", one of the earliest recorded audio stories of Doctor Who, takes place between this serial and "Planet of the Spiders". It was actually filmed during Jon Pertwee's soon-to-conclude tenure right before he left the role of the Doctor. However, it never made it to air and was reallocated to the shelves of the BBC Archives as an unfinished production. It was rediscovered in 2005, after Pertwee had passed, and included on Doctor Who at the BBC: Volume 3, a CD containing stories narrated by Elisabeth Sladen, who was still alive at the time of release.
- Agony Beam/Mind Rape: The refinery's security system.
- Author Tract: The "women's lib" section seems rather shoehorned into the story. It amounts to one scene, is superfluous to the plot, and is only raised briefly again at the end.
- Indeed, Ortron's Stay in the Kitchen vibe comes off more as an Informed Attribute. While Ortron is obviously dismissive of his Queen, it is hard to imagine him being more amenable to a young king. Also, when the chips are down, and Azaxyr threatens to rule Peladon, he is the first to proclaim that only the Queen has that right.
- Bait-and-Switch: Last time the Doctor was on Peladon the Ice Warriors turned out to be the good guys. Now they've gone back to being the villains again, with Azaxyr a member of a radical faction that wants to return to the Good Old Ways of war and conquest.
- Big Bad Duumvirate: Eckersley and Azaxyr.
- Les Collaborateurs: Eckersley conspires with the Ice Warriors for a stake in the trisilicate trade.
- Continuity Cavalcade: There are numerous mentions to the previous Peladon story.
- Convenient Coma: The Doctor can put himself into a coma, to avoid being killed by the refinery's alarm.
- Disappeared Dad: King Peladon is now dead of old age and his daughter has taken over the throne. We didn't even get to hear about the missus.
- The Dragon: Sskel to Azaxyr.
- Enemy Mine: Ortron and Gebeck's striking miners after the Ice Warriors show up.
- Everything in Space Is a Galaxy: Galaxy 5.
- Evil Chancellor: Although Orton's less "evil" and more of a Knight Templar.
- Fake Faint: Sarah Jane has Queen Thalira pretend to faint in order to distract the Ice Warrior guarding the door to the throne room.
- Flat-Earth Atheist: Vega Noxos (who belong to the Satyr alien race known as the vegan) He viewed the native Peladonian miners as "superstitious primitives" for their fear of Aggedor. Ironically he was killed by the fake ghost of Aggedor.
- Foreshadowing: Sarah Jane mentions the Doctor's saying, "Where there's life, there's hope," trailing off before the final word. Later, thinking him dead, she cries over his body. The Doctor, upon waking states, "Tears, Sarah?"
- HeelFace Turn: Chancellor Ortron
- Hermaphrodite: Alpha Centauri makes a second appearance, and is once again said to be hermaphroditic, voiced by a woman, and referred to as "he".
- History Repeats: After all the effort the Doctor put into making Peladon and the Federation a better place, it has only managed to get worse. Peladon has regressed from trust back to as it was during its medieval, crusader mentality-dominated days. Another crackpot advisor oversees its ruler and is even more execution slap-happy than his late predecessor, while the Ice Warriors are no longer friendly to the Doctor, but hostile. Oh, and another unintelligible mute man is the ruler's champion.
- Hostage Situation: The Martians gather a group of Peladonians, plus the Doctor and Sarah Jane, and threaten to kill them if the miners refuse to work.
- Judge, Jury, and Executioner: The Martian commander drops the trope name. He doesn't actually get to be the third one.
- Knight Templar: Orton is hostile to the Doctor and Sarah, tyrannical to the miners, and looks down on his own queen because she's a woman. He's also a genuinely loyal patriot of Peladon who quickly unites with the miners against the Ice Warriors and dies protecting his queen.
- The Mole: Eckersley.
- Multicoloured Hair/Skunk Stripe: The miners' hair, which has alternating bands of white and brown, as well as the other native Peladonians, who have stripes of red and white through their hair in various patterns.
- Music Soothes the Savage Beast: Aggedor is still enthralled by Venusian lullabies.
- Obvious Stunt Double: There's a fight scene where you get a good, clear look at the face of the Doctor's longtime stunt double, Terry Walsh.
- Public Secret Message: Gebek tells his miners to "cooperate with Commander Azaxyr like we've cooperated with Ortron". The catch being that they never liked Ortron and planned to overthrow him.
- Redemption Equals Death: Orton.
- Red Herring: For those who remember the last Peladon story where the Ice Warriors turned out to be on the Doctor's side. Here they are back to being villains again.
- Renegade Splinter Faction: Azaxyr and his crew are said to be members of an extremist Ice Warrior political group who are upset about their culture becoming good galactic citizens.
- The Revolution Will Not Be Vilified: Both averted and played straight; Gebeck's worker's rights movement is depicted sympathetically, but the attempts of Ettis to start an actual revolution are universally condemned.
- Ripped from the Headlines: This story was inspired by the 1972 miners' strike.
- "Scooby-Doo" Hoax: The evil ghost is really a hologram.
- Senseless Sacrifice: Ortron gives up his life to give Thalira a chance to escape. Unfortunately Thalira goes into shock on witnessing his death and is immediately recaptured.
- Sequel Episode: To "The Curse of Peladon".
- Stay in the Kitchen: Queen Thalira is not treated with much respect due to this. Sarah Jane evokes "Women's Lib" (using those words) to get her to stand up for herself.
- Strongly Worded Letter: Alpha Centauri threatens to make their displeasure known by sending an official communication to the Galatic Federation. This is during the middle of an armed uprising against the government.
- Unobtainium: Trisilicate
- The X of Y
- Yellow Rocks: Trisilicate
- You Will Outlive Your Usefulness: The Ice Warriors kindly inform the Doctor that they intend to kill him as soon as he's no longer useful to them.