The one with the dodgy dinosaurs.
The Doctor brings Sarah Jane back to 20th Century London, only to find it deserted. They're soon arrested as looters and, after a very nice photo session at the police station, duly try to escape. Although their attempt to run away fails rather miserably, the Brigadier is soon handed the files of all captured criminals of the day and fixes the "typical, absolutely typical" situation as soon as he can. Back with UNIT, the Brigadier explains that the city has been evacuated due to the sudden, random and unexplained appearances of dinosaurs.
The Doctor's plan to capture a dinosaur to track the energy from its disappearance back to the source is foiled through sabotage of none other than Captain Mike Yates - who, however, doesn't want the Doctor to come to any harm.
Sarah Jane manages to solve the plot before anyone else, getting kidnapped and almost murdered for her troubles... until she wakes up from an alleged "cryogenic sleep" on an eco-warrior spaceship headed for the planet "New Earth". When she tries to explain to its occupants that the nearest star is four light years away and they couldn't possibly get there within one generation, they lock her in the propaganda room to cool down. She escapes, naturally, and simply walks out of the "airlock" and up a flight of stairs to rejoin the plot back in London. The whole thing turns out to be a conspiracy led by a government minister, Charles Grover, who is using a Mad Scientist, Professor Whitaker, to clear London of people by bringing dinosaurs forward in time. They then plan to use a rudimentary time machine to return the Earth outside London to a pre-technological age, erasing most of the human race from history so that they can repopulate the planet with eugenically-selected "colonists". These are the eco-warriors, who are currently in a mocked-up spaceship in the minister's basement, believing they are on their way to colonize a new world.
To make things even more difficult for Sarah Jane and the Doctor, the head of the army controlling London, General Finch, is involved. Once the Brigadier and Sergeant Benton realize that Mike has become a Minion with an F in Evil to Grover, they allow the Doctor to escape (Benton by allowing a Venusian neck pinch and voluntarily letting the Doctor knock him out cold) and go confront the minister and his lackeys. Also, the Doctor drives Jon Pertwee's car for a bit, which is the most awesome vehicle in the universe.
The Doctor and the Brigadier raid the underground HQ of the conspiracy helped when Sarah enlightens the "colonists", who rebel. In a struggle with the Doctor over the controls of the time machine, the Doctor uses his Bizarre Alien Biology to withstand the time reversal and Reverse the Polarity. Grover accidentally transports himself and Whitaker back to the time of the dinosaurs.
The Brigadier offers Yates the chance to resign quietly. Benton revels in the fact he got a chance to punch a general in the nose, while the Doctor convinces Sarah to get back on board the TARDIS after tempting her with a trip to Florana, a place he thinks is one of the most beautiful planets in the universe. Following a futile attempt to ignore him, she merrily gives in.
Note: Episode 1 only existed for many years as a black and white film recording. For the DVD release a color restoration was attempted, with partial success, and the disc includes both versions.
- Action Girl: Sarah tackles a knife-wielding thug and stops him from stabbing the doctor.
- Affably Evil: Charles Grover. So courteous to everyone he meets, all the while planning to Ret Gone the Silurians and nearly all the human race in the name of Gaia.
- Air-Vent Passageway: Sarah gets locked in a closet and escapes through the air-duct.
- Anti-Villain: Yates, Grover and the chosen in Operation Golden Age.
- Being Evil Sucks: By siding with Operation Golden Age, Yates not only alienates his friends, but also finds himself reluctantly doing things that would harm them.
- Brainwashing for the Greater Good: The people on the "spaceship" voluntarily enter a brainwashing room to "remind themselves of the truth".
- Though it's not Mind Control, simply being locked in a room and forced to watch a greeny propaganda film that won't turn off unless the door is open.
- Brief Accent Imitation: The Doctor puts on a Cockney accent in order to impersonate a criminal.
- Bring It Back Alive: The Doctor and UNIT attempt to capture one of the dinosaurs alive.
- Conveniently Timed Distraction: UNIT soldier Private Bryson is ordered to get tea for the Doctor. While Bryson is out getting the tea, Yates arrives and holds the Doctor, Sgt. Benton and the Brigadier at gunpoint. When Bryson, unaware of what's going on, returns with the tea, Yates gets distracted and Benton uses this opportunity to disarm him.
- Cuffs Off, Rub Wrists: The Doctor and Sarah Jane rub their wrists when they get them off after they escape deportation. Later on, Sarah rubs her wrists after she'd been tied up on the fake spaceship.
- Easily Forgiven: Yates is simply removed from UNIT.
- Eco-Terrorist: The Golden Age crew are trying to Ret Gone the entire human race except themselves to wipe out environmental damage.
- Everything's Better with Dinosaurs
- Evil Luddite: The villains' motivation.
- FaceHeel Turn: Captain Yates.
- Faked Rip Van Winkle: This is the way the villains get Sarah out of the way - they knock her out and have her wake up aboard the Fauxtastic Voyage. She realizes it's fake when she realizes she still has a fresh bump on her head.
- Family-Unfriendly Death: There is a short but extremely gory shot of the dead Phillips with half his face ripped off.
- Fauxtastic Voyage: The colonists sincerely believe that they're on their way to a new planet. Apparently they don't have any mathematicians on board, or someone would question the fact that the trip is only three months long. (Given that the nearest solar system, Alpha Centauri, is four light years away, this would require travelling at sixteen times the speed of light, as Sarah Jane wearily points out).
- This gets Hand Waved by one of the colonists, who mentions some kind of new space drive.
- Getting Crap Past the Radar: A soldier can be seen reading a porno magazine.
- Gulliver Tie-Down: Proves insufficient to restrain the stunned T. rex when Sarah Jane's camera-flash rouses it.
- Hanging Judge: Shears, the Army officer that has to judge the looters, seems more annoyed with his job than anything else, so he spends about ten seconds on each case and finds everybody guilty.
- Have You Told Anyone Else?: General Finch to Sarah Jane. She didn't, but she left a note on the desk.
- Hit Me, Dammit!: Benton to the Doctor, when Finch orders him to hold the Doctor prisoner.
- Also used earlier when the Doctor and Lodge, one of the looters, stage a fistfight to distract a guard.
- Hoist by His Own Petard: Grover and Whitaker are sent back in time by Whitaker's machine after the Doctor reverses the polarity. Grover was foolish enough to make a break for the lever, and Whitaker failed to stop him from tugging it down.
- Horrible Judge of Character: Sarah gets captured twice through treating first Grover and then Finch as Reasonable Authority Figures without noticing their treachery. Particularly bad the second time, as she's incredibly trusting of Finch at a point when she knows anyone could be potentially in on the conspiracy. She openly lampshades it when Finch pulls a gun on her.Sarah Jane: Boy, I really don't choose my friends, don't I?
- The Igor: Butler.
- Immune to Bullets: All of the dinosaurs, for... some reason. Even grenades don't do anything other than mildly annoy them.
- Improbably Cool Car: Jon Pertwee's futuristic contraption, which fans affectionately named "The Whomobile".
- Karmic Death: Grover and Whitaker are sent back in time when their device is sabotaged by the Doctor. Best case, they manage to eke out a meagre existence for a few years before falling victim to some disease they won't be able to cure. Worst case, they get dumped right in front of a Tyrannosaurus and rapidly become dino-chow.
- Lack of Empathy: General Finch seems to think civiliansnote are, as he put it "wretched people".
- Landmarking the Hidden Base: Operation Golden Age is based under Trafalgar Square.
- Make It Look Like a Struggle: Benton is told to take the Doctor into custody. Once Yates has gone, and Benton has ordered the other soldiers away, comes this exchange:Benton: Right then, Doctor, you'd better get busy.
Benton: You'd better start overpowering me, hadn't you. You know, a bit of your Venusian oojah?
Doctor: Thank you, Sergeant Benton.
Doctor: Are you ready?
(Benton tenses and shuts his eyes tight. The Doctor uses the pressure grip at the back of Benton's neck to put him to sleep.)
- Misplaced Wildlife: Tyrannosaurus rex, Apatosaurus, and Triceratops were never indigenous to Great Britain, so a purely time-travel-based technology shouldn't have been able to bring them to London. Only the (unnamed) pterosaur averts this trope for certain; Stegosaurus may or may not, as its fossils have been found as nearby as Portugal.
- The Mole: Three of them.
- Obvious Stunt Double: The T.Rex is terrible to begin with, but it doesn't help that the model used for closeups is obviously completely different to the one used for the long shots.
- Obviously Evil: Double Subverted. General Finch's dour attitude and sinister mustache immediately mark him as the "inside man" the Doctor hypothesizes—but then Captain Yates, a longstanding ally of the Doctor, is seen conspiring with the villains, which seems to suggest that General Finch is okay after all—but then he has Sarah Jane kidnapped. Turns out they were both bad.
- Oh, Crap!: Sarah Jane, when she realizes she's revealed her findings to someone else in the plan.
- The One with...: The "making of" feature on the DVD describes this as "the one with the dodgy dinosaurs," referencing the fact that the terrible special effects are generally the first thing anyone talks about when discussing it.
- Pull the Thread: Sarah Jane does this with the Fauxtastic Voyage.
- Ptero Soarer: The Doctor is attacked by one. It looks more like a muppet than anything else, really.
- Ret Gone: The villains plan to do this to the entire human race except themselves.
- Reverse the Polarity: In this case, it throws Grover and Whitaker back in time, instead of the rest of the world.
- Right Behind Me
- Screw This, I'm Outta Here!: Once she realizes she's not in space, Sarah Jane walks out of the mock-spaceship, goes upstairs and rejoins the main plot.
- Sleeper Starship: Faked.
- Spoiler Title: Aversion: Part One was simply titled "Invasion". However, as always Radio Times printed the full title and spoiled the twist.
- Spotlight-Stealing Title: The serial's really about Operation Golden Age's schemes. The dinosaurs are secondary to the plot. Malcolm Hulke and Terrance Dicks had wanted to name the story Timescoop, but the higher powers vetoed it.
- Stiff Upper Lip: The Brigadier has no fear. Giant triceratops? Fine, he'll go stand in front of it waving a flare around for a few minutes.
- Tap on the Head: Sarah Jane is briefly knocked silly while trapped in a room when a wooden cross-beam falls on her head. The Doctor shows up shortly after and gets her out.
- Tempting Fate: In Part Two, the Doctor has built a stun gun to use on a dinosaur. He wants a docile and rather low-watt test subject, remarking, "Mind you, I wouldn't like to try it on a Tyrannosaurus Rex." Guess what pops up at the cliffhanger?
- Also true of the Brigadier boasting that the chains used to restrain said T. rex were unbreakable.
- Token Evil Teammate: Project Golden Age may not be good guys by any standard, but Whitaker probably qualifies as it's strongly implied he's only interested in advancing his research in contrast to his well-meaning accomplices, and he's much more willing and quick to use lethal force than they are.
- Treacherous Advisor: Sarah falls victim to this trope twice. First, the man she sees for help finding the villains' base turns out to be the one who helped them set it up. Then, after she escapes from him, she takes what she knows to the general who is coordinating the state of emergency, not knowing that, while she was away, he had also been revealed as a member of the conspiracy.
- Utopia Justifies the Means: Operation Golden Age, believing that the environment could not be saved, sent a shipload of volunteers on a Fauxtastic Voyage to "another world", to disembark after time had been reversed back to the Mesozoic and the rest of humanity (as well as all the Silurians) written out of history.
- Well-Intentioned Extremist: Operation Golden Age. Desperate to save the planet, people mean to move back time and Ret Gone everyone save their chosen few.
- Wham Episode: The suspenseful tone of the first episode, as well as the morally ambiguous villains and Phillips' bloody death heralded the darker tone the series would take in the Robert Holmes era. However, probably the most devastating event in the story is Yates's betrayal, not only marking the first time a regular companion had outright turned on the Doctor but also shattering the secure, cosy feeling of the UNIT family and heralding the series' return to the Doctor's more nomadic lifestyle. It's also a bit of a book-end, being the last Malcolm Hulke script, one of the defining Grey and Grey Morality writers and of the Pertwee era.
- Wham Line: "We left Earth three months ago." It turns out to be a Red Herring.
- What Happened to the Mouse?: The stegosaurus which briefly appears just before the Doctor's arrest isn't shown to vanish back to the past or be killed or captured by UNIT's forces. For all we know, it could still be standing there in the warehouse at the end of the story.
- The X of Y
- You Said You Would Let Him Live: The Golden Age nutjobs try to pull this on Yates concerning the Doctor.