The one with killer silverfish.
The TARDIS lands on the planet Telos, where a group of Earth archaeologists is trying to uncover the fabled Tomb of the Cybermen. The Doctor helps them get in, where they discover the creepy silent remains of the Cybermen's city.
After one of the expedition's members dies in an accident in the weapon testing chamber, the expedition leader, Professor Parry, decides that the expedition should return to Earth and be better prepared for the next expedition. Kaftan, one of the expedition's financial supporters, makes her servant Toberman sabotage the rocket so they can't get off the planet and have to explore further.
The Doctor helps them to open the way down to the tombs of the Cybermen, whereupon Kaftan and logician Klieg awaken the Cybermen from their cryogenic sleep and reveal that they are in fact there to revive the Cybermen, using their brains and the Cybermen's strength to conquer the universe.
As bad an idea as this would be, it turns out to be irrelevant anyway, as the tomb is just a giant logic puzzle designed to weed out everyone but the smartest people, whom the Cybermen judge worthy to be upgraded. The Cybermen punch their way out of the refrigerated tombs and attack the party accompanied by little slug-like Cybermats.
Toberman is captured and partially Cybermodified, but the party manages to escape the tomb area and stall off the (still weakened) Cybermen. The Doctor also uses electricity to disable the Cybermats and later the group finds a single Cyber-prototype weapon to keep the Cybermen at bay. At the same time, the Cybercontroller orders his Cybermen to return to their cryogenic tombs (as they are very low on energy), while Kaftan and Klieg attempt to betray the Doctor and friends by stealing their weapon and using it to seize control over the Cybermen, causing a very uneasy (and temporary) alliance between the Doctor and the Cybercontroller to ensure their mutual survival. Kaftan and Klieg end up being massacred by a lone Cyberman and with the mutual threat gone, the Cybercontroller turns against the Doctor's group, but Toberman's willpower allows him to temporarily overcome his Cyberconditioning and destroys one Cyberman, giving everyone the chance to escape. Finally, Toberman makes n Heroic Sacrifice by closing the entrance to the tomb and activating the door's defense mechanism, which electrocutes both him and the Cybercontroller, leaving the remaining Cybermen locked inside forever. The Doctor, Jamie and Victoria part ways with the surviving expedition's members and each go on their way.
This was thought to be lost for decades, until a complete copy was discovered in 1991 in Hong Kong — Prior to October 2013, it was the only complete story of Season 5, of Victoria, and of the first two years of Troughton.
Also, this episode turned Matt Smith (i.e. The Eleventh Doctor) into a fan of the show, and he has stated that it was watching this serial that inspired his own costume as the Doctor, most notably wearing a bowtie.
- The Assimilator: "You beeelong to Uzzz. You shall beee like Uzzz."
- Batman Gambit: The Cybermen's plan counts on someone eventually being smart, curious, and determined enough to get to them.
- Big Bad: The domed Cyber Controller. As Cyber Leaders hadn't been invented yet, this was the first time we saw a chain of command with the Cybermen. Also Klieg and Kaftan who serve as the human antagonists.
- Black Dude Dies First: Inverted. Toberman is the last (well, joint last) character to die.
- The Cavalry: Captain Hopper distracts the Cybermen with some smoke bombs, allowing The Doctor, Jamie and Professor Parry to get away just in time.
- The Chessmaster: The Second Doctor slyly manipulates events in a way that would make Seven proud.
- Continuity Nod:
- Creepy Monotone: The Cybermen.
- Machine Monotone: They speak with a harsh monotone buzz.
- Deadpan Snarker: Victoria.
- Disproportionate Retribution: After retrieving the experimental cyber-gun, Klieg launches into a lengthy monologue about how much he's going to enjoy killing the Doctor and his friends with it. At this point, mind, the only thing that the Doctor has done to Klieg is make him look stupid a couple of times.
- Dwindling Party: Only two members of Parry's expedition are still alive at the end.
- The End... Or Is It?: When Jamie asks the Doctor if this is the end of the Cybermen the Doctor says he never likes to make predictions. As they leave a Cybermat is shown moving towards Toberman.
- Evil Is Not a Toy: Klieg never learns this. Well, technically he does, but it's a rather fatal lesson...
- Exposition of Immortality: The Doctor, when prompted by Victoria, reveals he's over four-hundred years old. He does have to think about it for a moment, though.
- Family-Unfriendly Violence: According to the director Morris Barry, the story got him into serious trouble with The BBC for the scene where Toberman kills a Cyberman. There is a special effects shot where awful thick white fluid begins spewing out of its crushed lung unit while it spasms and groans itself to a painful death. Barry claimed the BBC told him it was too much but "children adored it".
- Food Pills: And suddenly Victoria is not hungry.
- Forced Perspective: There are some very convincing Forced Perspective model shots of the humans' spaceship.
- Hand Blast: Several Cybermen fire electrical bolts from their hands.
- Heel–Face Turn: Toberman.
- Heroic Sacrifice/You Shall Not Pass!: "They will not get past Toberman."
- Hollywood Darkness: The tomb interior is remarkably well-lit considering it's all underground with no visible light sources. Lampshaded, with Jamie remarking on it and receiving a technobabble explanation about the walls being designed to be phosphorescent.
- It's Quiet... Too Quiet: After Hooper and Callum manage to re-open the entrance to the undertomb, they listen for any sound from the party that was trapped down there. Victoria remarks that it's very quiet, and Hooper says it's too quiet.
- Just for Pun: See Lame Pun Reaction below.
- Karmic Death: Kaftan and Klieg are killed by the Cybermen - the very creatures they wanted to bargain with.
- Lame Pun Reaction: Jamie does not appreciate the Doctor's attempts at wit.Doctor: The power cable generated an electrical field and confused their tiny metal minds. You might almost say they've had a complete metal breakdown! [Jamie groans] I'm so sorry, Jamie.
- Large Ham: Klieg can get very loud.
- Last Villain Stand: After the Cybermen have either been sealed back in their Tombs or destroyed, the Cyber Controller makes a last attempt to leave the Tombs. This is stopped by the Heroic Sacrifice of Toberman, who closes the doors giving them both an electric shock. Although it is revealed in "Attack of the Cybermen" that the Controller survived.
- Locking MacGyver in the Store Cupboard: Well, more like Locking Both Traitors In The Weapons Testing Room, which is even dumber.
- Logical Fallacies: Victoria reaches the (correct) conclusion that the Doctor is older than he looks based on nothing more than the fact that he's a time traveller.
- Look Behind You: Twice when Kaftan is holding Victoria at gunpoint, Victoria has a panicked reaction to a cybermat sneaking up behind her. The first time there really is a cybermat, but Kaftan thinks it's just a trick until the cybermat attacks her. The second time it's just a bluff, and it works.
- Malevolent Mugshot: The tomb complex where the Cybermen lie in suspended animation has big Cyberman-heads stenciled on the walls here and there.
- Not Quite Dead: The Cyber-Controller, requiring Toberman to make a Heroic Sacrifice.
- Obviously Evil: Everything Kaftan does screams 'up to something'. The Doctor notices, yet leaves Victoria alone with her. Perhaps justified, since he explicitly asks Victoria to keep an eye on her, presumably intending to have someone he trusts watch over her rather than just leave her to get up to all kinds of mischief unobserved.
- Oh, Crap!: The Doctor and Jamie when they see the Cyber-Controller getting back up.
- Only Smart People May Pass: The controls to the tomb are a giant symbolic logic puzzle. Justified, in that the Cybermen want their new race to be built from only the best - that is, people smart enough to figure out the puzzle.
- Playing Possum: First Kaftan fakes being unconscious (though not dead), and later on the Cybercontroller plays possum.
- Redemption Equals Death: Both Kaftan and Toberman go down fighting the Cybermen they were originally trying to recruit. Averted with Klieg who's just literally Too Dumb to Live.
- Scary Black Man: Toberman, with a surprising dose of Hidden Depths.
- Sealed Army in a Can: The Cybermen are dormant in their tombs. In the end, the Doctor ensures that they stay that way.
- Sealed Evil in a Can: The Cybermen sealed themselves in a can figuring whoever could unseal it had abilities that would make them stronger.
- Sequel Hook: From the ending shots, it's quite obvious that this is not the end of the Cybermen.
- This could be a contrast to the previous story's "final end" of the Daleks. The producers wanted to get rid of the Daleks and use other monsters, so they show the Cybermen are still around.
- Sigil Spam: Many of the surfaces in the Cybermen's secret lair — including the front door — are emblazoned with a stylized representation of a Cyberman head.
- Slipping a Mickey: Kaftan drugs Victoria's coffee to knock her out.
- Smug Snake: Neither Kaftan nor Klieg are nearly as clever as they think they are, but Klieg in particular spends a lot of time strutting around inadvertently letting the Doctor make him look stupid. They also keep telling themselves they'll be able to control the Cybermen right up until they are deleted.
- Straw Vulcan: The Logicians.
- Stay in the Kitchen: The white male archaeologists divide up several investigation parties for exploring the tomb. Victoria and Kaftan, as 'the women', are asked to stay behind in the first room for their safety, accompanied by the team's only black man for their protection (keeping him out of the way as well). Victoria is unimpressed and insists on taking them all investigating, then promptly gets herself shut into a sarcophagus and has to be rescued (although by Kaftan). Keep in mind Victoria is from the 1860s and has more progressive views of gender roles than anyone else in the plot.
- Take Over the World: Kaftan and Klieg plan to use the Cybermen technology to do this.
- Tempting Fate: Jamie is confident the ropes he's tied will keep the Cybercontroller down.
- Too Dumb to Live: Klieg. Most of the others too, seeing as they always leave guns lying around for someone to grab.
- TV Genius: Klieg and Kaftan. You apparently need serious logic skills to join the Brotherhood of Logicians, but it seems they aren't so interested in "common sense" or "not being a batshit crazy megalomaniac".
- Utopia Justifies the Means: Klieg and the rest of the Brotherhood of Logicians intended to take over the world with the aid of the Cybermen. Bit of a logical fallacy there ...
- Of course, the Doctor eventually manages to goad Klieg into revealing that, for him, at least, logic and utopia are just excuses; at the end of it all, he's just a power-mad nutcase.
- Villainous Breakdown: Klieg just can't seem to grasp that the Cybermen never will cooperate and that his plan was doomed to fail from the start. At the end, he names himself the new Cybercontroller, right before he is killed by a Cyberman.
- What the Hell Is That Accent?: Klieg and Kaftan are pretty much generic shifty "foreigners" with an accent that doesn't exist outside of wherever they sustained their head injuries. Hopper and Callum are Americans, but you wouldn't know it if their dialogue wasn't peppered with what the writers thought were Americanisms.
- Klieg's actor was a Cypriot, if that makes it any clearer.
- Women Are Wiser: Of a sort; each logician is as bad as the other, but of the two Kaftan clearly has her head screwed on a bit better than Klieg.
- The X of Y: Considerably rarer for the Cybermen than the Daleks in the classic series, for some reason. This is the first of just three.
- You Shall Not Pass!: The Doctor and Jamie attempt to close the electrified doors to the tombs, sealing the Cyber Controller inside. When they realize that doing so would kill them as well, even if they could overcome the Controller's attempts to force its way out, the enormous Toberman pushes them aside, declares, "You shall not pass Toberman: The door is closed," and forces the doors shut, killing himself and (apparently) the Cyber Controller.
- You're Insane!: Towards the end, the Doctor rather awesomely humours Klieg's delusions of grandeur, purely for the purpose of getting Klieg wound up and ranting like a megalomaniac so that he can use this as a put-down.The Doctor: Well, now I know you're mad. I just wanted to make sure.
- Zeerust: Food pills and rocket ships for all. Although some of the team are wearing very modern clothing.