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Recap / Doctor Who S1 E5 "The Keys of Marinus"

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"I don't believe that man was made to be controlled by machines. Machines can make laws but they cannot preserve justice. Only human beings can do that."
The Doctor

The one with evil scuba diver aliens.

Back with science-based action this time, as the TARDIS arrives on Marinus, on an island of glass in a sea of acid. It turns out this island is the location of the "Conscience of Marinus", a mind-controlling machine that has been used for centuries to keep the peace. However, the villainous Yartek and his Voord warriors wanted to capture the machine and use it for evil, so the four eponymous Keys of Marinus without which the machine wouldn't function were scattered over the planet in secret locations.

Now Arbitan, the "Keeper of the Conscience" has rigged the machine so the Voords can't use it and the Doctor and companions must go and retrieve the Keys of Marinus so it can be switched back on again.

The Doctor and his companions are forced to play along. They team up with Arbitan's daughter Sabetha and her fabulously dressed boyfriend Altos. After adventures in a series of inventive locations (including a building under attack by ambulatory plants and a city in which Ian is accused of murder and finds that he's guilty until proven innocent), the travellers return with the Keys, only to find that Yartek has killed Arbitan. Yartek forces them to hand over the keys, but Ian passes him a fake one and the machine blows up in his face, killing him and the other Voords.



  • Absentee Actor: The Doctor is absent from episodes three and four in order to allow William Hartnell a holiday.
  • Adventure Towns
  • All There in the Script: Terry Nation developed more background in his script than was made explicit onscreen in the finished production. The Voord were alien invaders who took advantage of the people of Marinus, rendered vulnerable by the pacifying effects of the Conscience. The Conscience was then deactivated to allow the Marinians to fight the Voord, and over the centuries, the time they spent on Marinus meant that the Voord, too, could now be affected by the machine. Therefore, Arbitan dispatched agents to recover the keys which would reactivate the Conscience and allow him to finally defeat the invaders.
  • Attempted Rape: While never stated, it's pretty obvious that Vasor has this in mind for Barbara. Quite a shocking moment for a series like this.
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  • Awesome Anachronistic Apparel: After spending months in ancient China as Marco Polo's guest, Ian keeps wearing his Chinese clothing for this adventure just for the heck of it.
  • Better Manhandle the Murder Weapon: How Ian finds himself accused of murder.
  • Big Damn Villains: Vasor takes Susan hostage, but the warriors from the ice kill him as they hack their way through the door.
  • Bound and Gagged: Susan in Episode 6.
  • Brain in a Jar: The Morpho of Morphoton.
  • Brainwashing for the Greater Good: The Conscience. Interestingly, not treated as an inherently bad idea. We get the Doctor's quote at the end, but it had harmlessly kept the peace for ages, and the one human-run justice system we see is a Kangaroo Court where you are guilty until proven innocent. There's just this pesky problem of bad guys trying to hijack the thing.
  • Call-Back: Ian is still wearing the costume given to him by Marco Polo in the previous serial.
  • Chekhov's Gun: The fake Key.
  • The Corpse Stops Here: Probably the earliest example in the series. And Ian is accused of killing him.
  • Crapsaccharine World: Morphoton.
  • Death World: The planet Marinus. Glass beaches lapped by acid seas. Jungles full of hostile plants and deadly mechanical traps. Frozen wastelands patrolled by packs of man-eating wolves. Bodiless, telepathic slavers. Then there's the WAR....
  • Department of Redundancy Department:
    The Doctor: No. Impossible at this temperature. Besides, it's too warm.
    • Also:
      Barbara: I believe you are under some deep form of deep hypnosis.
  • Descending Ceiling: Barbara is nearly done in by a spiked one.
  • Dismantled MacGuffin: The Doctor and companions are sent to collect the Keys (scattered throughout the planet Marinus) that control the Conscience Machine, which made everyone peaceful on the planet till it malfunctioned.
  • The Evils of Free Will: The villains planned to use the Conscience Machine to control the planet.
  • Fakin' MacGuffin
  • Faux Affably Evil: The Brains of Morphoton, Vasor.
  • Gadget Watches: The teleport bracelets.
  • Gotta Catch Them All: The quest for the keys.
  • He Knows Too Much: Ayden.
    • Also why the Brains of Morphoton decide Barbara must die.
  • I Have You Now, My Pretty: Vasor's intentions towards Barbara are never explicitly stated, but they're not exactly difficult to guess.
  • I Never Said It Was Poison: Susan is kidnapped and her captor forces her to speak to Barbara over a futuristic alien phone. Later, the kidnapper accidentally lets it slip in conversation that she is aware they have spoken to Susan, even though it was not mentioned. This allows Barbara to realize her guilt.
  • Kangaroo Court: Ian's trial for murder. Under the laws of the alien city where the trial takes place, Ian is guilty until proved innocent; he is even described as "the accused and convicted" before the Doctor has even begun to defend him.
  • Let's Split Up, Gang: Constantly. The gang splits up to search in more places in the same time, and those groups occasionally split to cover more ground. Damsel in Distress-ness ensues.
  • Lotus-Eater Machine: Morphoton.
  • MacGuffin Guardian: One of the keys is in a block of ice and guarded by several warriors who come to life when it is thawed out.
  • Malevolent Architecture: In part 3, a building full of death traps houses one of the titular artifacts.
  • Mr. Fanservice: Altos, with his clothing covering abut as much of his legs as a pair of briefs would.
  • Multicultural Alien Planet: The protagonists visit a different area of Marinus in each episode, each with its own inhabitants and culture.
  • Names to Run Away From: The Morpho.
  • Nice Hat: The judges from the fifth episode.
  • No Name Given: Darrius is never referred to by name in the on-screen dialogue of "The Screaming Jungle"; his name appears only on the closing credits.
  • Patrick Stewart Speech: The Doctor delivers the page quote.
  • People in Rubber Suits: The Voords. Possibly. Perhaps the suits have fused with their actual bodies.
  • Shifting the Burden of Proof: Jurisprudence in Millennius requires the defense to prove a negative.
  • Single-Biome Planet: Defied. Each episode takes place in a different environment within Marinus.
  • Trouble Magnet Gambit: Vasor is the former Trope Namer.
  • Wacky Wayside Tribe: The serial is entirely made of this - the characters have to collect Plot Coupons from various locations on the planet, each of which has a different culture and threat. There's a Lotus-Eater Machine world that only Barbara can see through, a murder investigation world where the Doctor is a lawyer and has to use The Perry Mason Method to save Ian after he picked up the knife, an ice world where they have to fight ancient guardians and so on.
  • The X of Y: Most of the individual episodes count as well, with the 1st, 4th, 5th and 6th being called The Sea of Death, The Snows of Terror, Sentence of Death and The Keys of Marinus respectively.


Example of: