The one with a bite-sized Master.
Our story begins with a group of desert dwellers on the planet Sarn. They worship a god named Logar and they have a Chosen One, named Malkon, who is declared so because of a special double-triangle symbol burned into his arm. The people of Sarn like to bicker on if their god really exists or not, and continue to do little else for the rest of the story.
In the TARDIS, the Doctor hasn't taken Tegan's decision to leave all that well. He curses the Daleks for a bit before Turlough tells him to snap out of it. However, before either of them can get any more lines in, a random scream pierces the TARDIS control room. Why, that must be Kamelion, and he's in danger! You remember Kamelion, right? He showed up at the tail end of the last season and vowed he'd be a loyal companion of the Doctor! ...And then he never bothered to show up again until this episode.
It turns out Kamelion is lying on the ground sparking as a cable stretches into a wall of the TARDIS set. But the Doctor isn't especially worried, as he just leaves the guy laying there on the ground.
Over on Earth, the same double-triangle is mysteriously found engraved on what looks like an ancient golden dumbbell on an island nation off the coast of Africa. It's found by an American archaeologist and his stepdaughter: college student Perpugilliam "Peri" Brown. Peri wants to go off on holiday to Morocco instead with some guys she's just met, but her stepfather refuses and leaves her stranded on the boat alone, because he's a terrible person. Peri, being of completely sound mind and judgment of course, decides to take the rather huge artifact with her as she leaps off the boat they've been traveling on and tries to swim to shore. Of course, she nearly drowns.
Luckily, the TARDIS is right nearby. Apparently, the magical alien dumbbell is sending out a distress call of some sort. Turlough just happens to see the drowning Peri and decides to save her, only to go through Peri's belongings once he gets her into the TARDIS. Smooth. Either way, Turlough finds the golden dumbbell of the ancients and is shocked by the double-triangle, as he has the exact same symbol burned onto his arm. The Doctor, for his part of this episode, was off having tea while waiting for another bit of the signal. Once he comes back, the Doctor sets off for the source of the signal — taking everyone to the planet Sarn. The Doctor and Turlough go out to look around.
Peri is immediately jumped by Kamelion, who has now taken the shape of... Peri's... step... father. Because Kamelion, being influenced by psychic projections, has apparently picked up on some strong negative emotions Peri has towards the man. Soon enough, though, Kamelion turns into the Master instead. The robot made to be a slave to the Master is now again a slave to the Master. No one seems very surprised by this.
The Doctor and Turlough find the Sarn people and the Doctor quickly informs them that they live in an active volcano system. Not only that, but they happen to be living inside lava tubes and vent chambers. Before much more happens, though, Turlough asks about that double-triangle symbol through showing it off on his arm. They praise him as a second Chosen One, and Turlough realizes that Malkon may well be his brother. And then Peri shows up, having run out of the TARDIS to flee from the incredibly-creepy Kamelion to let Turlough know that someone called "the Master" has just shown up.
Kamelion (still looking like, and controlled by, the Master) shows up and promptly takes over the role of "the Outsider" in the local religion, which basically means he gets to run around and tell people what to do. As silly as this seems on paper, in action it just means that Anthony Ainley gets to be awesomely hammy — throwing his arms around like a preacher on Christmas morning. The Doctor starts acting like a complete and utter asshole to Kamelion, claiming he's trying to free the distressed droid. Then the Doctor is thrown in jail.
It turns out that Sarn is an old colonization attempt by Turlough's people, and it just so happened to be a prison world. Turlough is also a criminal-by-relation, his father having fought in a war, and having ended up on the losing side. Meanwhile, Peri is taken to the Master's TARDIS by Kamelion and she's forced into moving a small box. Looking inside the Master's "control box," she quickly sees why the Master needed Kamelion... he's doll-sized. So he runs around his TARDIS while Peri tries to crush him like one would an errant cockroach.
Apparently, he accidentally shot himself with an advanced Tissue Compression Eliminator and needs some special regenerating gasses from the planet Sarn in order to return to normal. However, the gasses are stored in the core of the planet, and the Master's dinking around has caused the place to become geologically unstable. Turlough swallows what little pride he has left and calls his people with the wreckage of a crashed spaceship, where his brother also happened to come from. They agree to send a ship to recover those who remain on the planet. Meanwhile, Peri and the Doctor try to stop the Master's super awesome plan... but not before the Doctor decides to use the regenerating gasses to heal up a few of the sick and wounded by setting them on fire.
However, Peri and the Doctor aren't really able to stop the Master. Instead, the Doctor is just barely able to short-circuit Kamelion, giving the robot what the Doctor calls "an electronic heart attack." Kamelion then, in what amounts to Hulk-speak, begs for the Doctor to kill him off. Using the Master's Tissue Compression Eliminator, the Doctor coolly ends Kamelion's life, reducing him to a silver action figure. Meanwhile, the Mini-Master is finally absorbing the regenerative gasses of the planet, and grows back to size...
...until the blue flames that represent the gasses turn to real flames and burn the Master to death as the Doctor stares on in Dull Surprise.
With the Master supposedly dead (again), the Doctor and Turlough part ways. The war "criminals" have long since been forgiven and Turlough's exile is lifted. Peri begs to follow the Doctor along on more adventures. and he agrees, hesitantly, and welcomes her to the TARDIS.
- Absentee Actor: The only story in Peter Davison's entire run to not feature an appearance from Janet Fielding as Tegan, who departed in the previous story but would go on to make a cameo appearance with the rest of the Fifth Doctor's companions in "The Caves of Androzani".
- Absent-Minded Professor: Having a drink at a cafe, the Doctor runs off when his tracker activates, leaving some decidedly non-Earth coins as payment and becoming an unintentional dine and dasher.
- Back for the Dead: Kamelion makes his second appearance herenote ... only to die at the end of the story.
- Beach Episode: Part 1, set on the coast of Lanzarote, providing an excuse for high levels of Fanservice from Nicola Bryant and Mark Strickson. Actor David Tennant and producer Phil Collinson reminisce fondly about this episode in the hidden commentary on "The Five Doctors". Even Peter Davison's usual cover-all outfits are somewhat relaxed.
- Big Little Man: Done as a Cliffhanger reveal when it turns out the Master has accidentally shrunk himself to a small size, and has been directing the shapeshifter robot that everyone thinks is him from a control box.
- Birthmark of Destiny: Malkon's brand is interpreted as one of these by the people of Sarn.
- Bittersweet Ending: Turlough leaves the TARDIS and the Doctor is forced to kill Kamelion, but Turlough gets to return to his home planet with his brother, and the Doctor is joined on his travels by Peri.
- Chekhov's Volcano
- Dark and Troubled Past: The Turlough brothers
- Deadly Gas: Inverted - the numismeton gas is healthsome and good.
- Deep Cover Agent: According to Turlough, the Trions had undercover agents on every civilized planet, including Earth.
- Distress Call
- Dropped a Bridge on Him
- Dull Surprise: The Doctor's slack-jawed blank expression as the Master supposedly burns alive.
- Establishing Character Moment: Peri is introduced with a closeup of her in a bikini, indicating what kind of companion she is.
- Fanservice: This episode is pretty much the apotheosis of John Nathan-Turner's "something for the dads" policy. Although it certainly gives "something for the mums" - Turlough in speedos and a soaked shirt, anyone?
- Forgiveness Requires Death: Timanov and the elders choose to remain on Sarn and perish.
- Ham-to-Ham Combat: This adventure features a particularly hammy Peter Davison taking on an even hammier Anthony Ainley. And it is glorious.
- Peter Davison notes on the DVD's "making of" documentary that Ainley originally tried to underplay the role much more than he does in the finished product. However, the serial's director, Fiona Cumming was known to favour very hammy, over-the-top performances from her actors, and made Ainley turn his performance Up to Eleven.
- Hazmat Suit: A key plot point is that the hazmat suits are mistaken for gods.
- Heroic BSoD: The Doctor seems to be going through this at the start, following Tegan's abrupt departure.
- Home Sweet Home: Turlough's motive for leaving is that he has a chance to go home, and as a hero no less.
- Hot Scientist: Peri's stepfather.
- I Just Shot Myself In The Face: Strongly implied that this is at the root of the Master's problems.
- I Lied: Kamelion as the Master promises the Sarns treasure if only they'lll help him get into his TARDIS. He makes for the door immediately, ignoring Timarov's shouts, and gloatingly insults his gullibility.
- Kill It with Fire: The Doctor tries this on the Master. He gets better.
- Long Lost Sibling: Malkon
- Male Gaze: Peri has had less than four minutes of screen time before she's in a bikini, with a long close-up shot of her body before panning up to her face. This set a precedent for pretty much her entire tenure on the show.
- Mark of Shame: It's revealed that Turlough has one of these on his arm marking him as a political prisoner on Trion. His brother has the same mark, but grew up believing it made him The Chosen One since that was how the locals of the planet he landed on regarded him.
- The Master
- Mercy Kill: The Doctor does this to Kamelion.
- Moral Dissonance: Burning the Master alive. For a guy who's supposed to be fixated on saving people, he pretty much kicks back, lets the Master burn, shrugs, and walks away.
- No One Could Survive That!:...well, unless they had Joker Immunity, anyway.
- No-Sell: Peri to the Master's mind-control powers.The Master: I am the Master and you will obey me.Peri: So what? I'm Perpugilliam Brown and I can shout as loud as you can!
- Oh, Crap!: The Doctor's life is saved when one of the Sarns "is killed defending him". And then the Master-controlled Kamelion appears on the scene...
- Ooh, Me Accent's Slipping: Nicola Bryant, again.
- Distinctly non-American phrases like "do a bunk" don't help either.
- Penal Colony: Sarn
- Perverse Puppet: Good ol' Kamelion. Good riddance to bad props.
- Purely Aesthetic Glasses: They're baaaack!
- Re-Cut: The DVD version includes a "movie" edit with new CGI special effects, including CGI volcanic gases being added to many of the Sarn scenes to make the increasing instability of the planet clearer. However, some dialogue is actually cut to make room for the new effects sequences.
- Robot Buddy: Ditto.
- Scenery Porn: Starts out like this, but after the first episode the story actually starts doing a good job of using the Lanzarote location, making the titular planet look far more convincing than it would have been if it were just filmed in a quarry.
- Shout-Out: There are parallels with the novel She, whose title character renews herself periodically by bathing in a magic flame.
- Shut Up, Hannibal!: See the page quote. Especially good as the Master was trying to hypnotize Peri at the time. It is also the only time he ever fails to hypnotize a human being straight out, and no reason for this is ever given. Apart from the fact that she can shout just as loud as he can. Though strictly speaking it's not the Master, but Kamelion as the Master who fails to hypnotise Peri.
- Thicker Than Water: Turlough is ready to kill when Malkon is hurt. The Doctor says it would do no good, whereupon Turlough reveals that they are brothers.
- Waistcoat of Style: The Doctor swaps his frock coat and cricket jumper for a stylish tapestry-patterned waistcoat. Well, he is on holiday after all.
- We Meet Again: Kamelion, in the guise of Howard, strolls into the TARDIS console room.
- Doctor? We meet again.
- What the Hell, Hero?: Yeah, the Doctor's kind of an ass to Kamelion, isn't he? Peri seems to call him out on that during the story, but the Doctor hand-waves it by claiming he's trying to free the poor distressed robot. By being a dick to it. Riiiight.
- Who Wears Short Shorts?: Turlough sports a nice pair.
- The X of Y