The Mysterious Planet
The Mysterious Planet was the unbroadcast title given to the first four episodes of The Trial of a Time Lord, the season-long story that constituted season 23 of Doctor Who. The story marked the first appearance of the Inquisitor and the Valeyard, two characters who would appear throughout the season, along with Sabalom Glitz, who would appear again later in the season and also in Season 24. With this chapter, the series returned to half-hour episodes. Also beginning with this story, the series was now completely produced on videotape (with the exception, in this story, of a brief special effects sequence in Episode 1).
With this episode, Peter Howell’s rendition of the Doctor Who theme was exchanged for a mysterious and surreal arrangement of the theme tune composed by Dominic Glynn. It would remain in use solely for season 23 and close out Colin Baker’s era on the series.
This story also introduced some costume changes for the Doctor & Peri. The Sixth Doctor entered his second (and last) full season with a red check vest & cravat and a bright pink watch chain. To help viewers discern between scenes taking place in different points in the Doctor’s timeline, scenes set in his past feature him donning his original turquoise cravat & neon green watch chain for the last time; the following story would feature the Doctor’s full new outfit in both past and present scenes, and the one after that featured a completely different vest & cravat for the archival scenes, which are set in the Doctor’s future.
Notably, Nicola Bryant’s character Peri Brown starts wearing more conservative clothing from here out, after spending most of her appearances in loose-fitting and often revealing outfits. Her wardrobe change was a result of complaints that her provocative clothes were inappropriate for younger Doctor Who viewers.
Episode 1 (Trial of a Time Lord Part 1)
The TARDIS materializes in a corridor, and the Sixth Doctor emerges, bewildered and alone. He walks into a room, where he is put on trial for conduct unbecoming a Time Lord. The Inquisitor notes that the Doctor has been on trial previously. The Valeyard states he will argue that the Doctor was shown too much leniency on that occasion. The Valeyard opens the case by using the Matrix to show the Doctor’s actions on the planet Ravolox.
The Doctor and Peri arrive on Ravolox, which is virtually identical to Earth. He tells Peri that the official records state that the planet was devastated by a fireball, but the forest they are walking through suggests otherwise. They are seen by Sabalom Glitz and Dibber, who attempt to shoot the Doctor. He moves off just in time. Glitz and Dibber discuss their plan to destroy the “L3 robot” by sabotaging its light conversion system, which has been turned into a totem by a primitive tribe.
The Doctor and Peri explore a cavern. Peri discovers a sign saying “Marble Arch” — a London Underground sign. This means that they are on Earth. Peri begins to mourn for her planet.
The Doctor interrupts the replay to ask what the relevance of this is. He then also asks why Peri is not with him on the station. The Valeyard answers that she is where the Doctor left her, and states that the Doctor’s evident temporary amnesia — a side-effect of being taken out of time — should soon pass.
As the Matrix resumes showing the events on Ravalox, Peri is still upset. The Doctor goes into the complex alone. Two masked figures appear and capture Peri. Meanwhile, Glitz and Dibber are brought before Katryca, Queen of the Tribe of the Free. Glitz claims that the totem attracted the fireball that devastated Ravolox, and asks for it to be taken down. The Queen tells him that others have asked for the totem to be dismantled, and none have succeeded. Glitz and Dibber draw their guns, but are overpowered and locked up.
The Doctor finds an underground complex and picks up a bottle of water. This sets off an alarm, and people enter and subdue him. He is accused of stealing water, and sentenced to be stoned. The Doctor tries to block the rocks with his umbrella, but is knocked unconscious.
The Valeyard proposes that the inquiry into the Doctor’s activities should become a full blown trial, with the penalty being the termination of his life…
Episode 2 (Trial of a Time Lord Part 2)
Other officials arrive and break up the stoning. The Doctor is still breathing. Before he can be killed, Merdeen receives a message from the Immortal stating that he wishes to question the Doctor. The Immortal, revealed to be a huge humanoid robot, commands its two assistants to release the service robot.
Peri is brought before Katryca, who informs her that as there are few women, she will need to take many husbands as a member of her tribe. She is put in the same prison as Glitz and Dibber. They tell Peri their plan to destroy the robot. They are taken back to Katryca, who tells them that Glitz will be sacrificed because of his attempt to destroy the great totem.
The Doctor is taken to the Immortal, who introduces itself as Drathro. It commands the Doctor to work with the two assistants. The Doctor identifies the problem, and tries to leave in order to fix it, but Drathro does not allow him to, as his instructions are to maintain an underground system. The Doctor electrifies the robot and his assistants and escapes. Drathro sends the service robot to track down the Doctor. Meanwhile, Peri, Glitz and Dibber overpower the guards and escape. Dibber remains behind to plant a bomb on the black light converter, whilst they go to the underground complex.
In the Marb Station, Merdeen tells Balazar that there has been no fire for hundreds of years, and he should leave the complex. They encounter the Doctor, and Merdeen implores him to help Balazar escape. Peri, Glitz and Dibber, pursued by tribesmen, find the Doctor, and they flee into the Marb Station, but are trapped between the tribe and the service robot. When Peri asks what they should do, the Doctor replies, “I don’t know. I really think this could be the end. . . “
Episode 3 (Trial of a Time Lord Part 3)
The Doctor and Peri are saved when the tribesmen shoot at the service robot and disable it. The Doctor tries to re-enter the underground complex, but the tribesmen insist they all return to the village. There, the Doctor is brought before Katryca. She is unimpressed with his explanation of the true nature of the totem and puts them all back in the prison cell.
Glitz confirms that the planet is actually Earth. Drathro reactivates the service robot and sends it to the village. It breaks into the building with the Doctor, stuns him after an attempted handshake and takes him away. The tribesmen disable the service robot and decide to attack the Immortal’s castle to steal his technology, believing that they have killed him. Peri rescues the Doctor from the service robot. They set off to the underground complex to stop Katryca and disable the black light system.
The Doctor and Peri encounter Merdeen, one of Drathro’s train guards, in the corridors of the underground complex. He tells them that he is hunting. When the Doctor asks who his quarry is, he looks at the Doctor and says, “You”. He raises a crossbow weapon at the Doctor and fires…
Episode 4 (Trial of a Time Lord Part 4)
Katryca and the tribesmen arrive at the castle, where they are confronted by Drathro. He electrocutes Katryca and dismisses the rest of the tribe. The Doctor enters Drathro’s domain, promising to help repair the black light system. However, he determines it to be beyond repair, and tells Drathro that he must shut down the black light system to prevent a massive explosion. Drathro refuses as it would mean its own destruction. The Doctor pleads with him, saying that the explosion could destroy the entire universe. That makes Drathro determined to allow what he thinks is a unique event.
Balazar and Peri plead with Merdeen to help them, noting that he would die if the converter exploded. Glitz and Dibber arrive and follow them into the castle through a food chute. Drathro tries to kill them by turning on the food processing system, but Dibber shoots him through the wall. Glitz tells Drathro that they have black light on their ship, and offers to take the robot to the Andromeda Galaxy. Drathro agrees, and leaves with Glitz and Dibber.
The Doctor realizes that the black light system has already begun to self-destruct. All he can do is prevent it starting a chain reaction. The system explodes, but the blast only destroys the castle, and as a result Drathro collapses. The Doctor and Peri leave Merdeen and Balazar to take the remaining inhabitants to a new life on the surface.
The Doctor announces to the court that he has saved the Universe, and starts to present his defense. The Valeyard warns the Doctor that he has more evidence to come, and that the court will demand the Doctor’s life at the end.