The one where GOD HIMSELF comes back.
After receiving a garbled message from the White Guardian (and almost blowing up the TARDIS in the process), the Fifth Doctor, Tegan and Turlough are taken by the TARDIS to what appears to be an Edwardian sailing ship. The Doctor and Turlough find out that the sailors have absolutely no idea how they came aboard the ship nor who their captain is. (But they got paid in advance, so don't give a damn.)
Meanwhile, Tegan is left in the TARDIS in case the White Guardian sends another message. He does: they have to win "the race" and it's "winner takes all". But before she can get to the Doctor with this urgent information, she runs into the ship's handsome but creepy first mate, Marriner, who tells Tegan in an equally creepy voice that he will take her to her friends. The four of them eventually meet in the bridge, where the Doctor looks at the ship's map just in time for the show's first cliffhanger: the ship is actually a spaceship, and it's racing with other period Earth ships through the solar system. Because it'd be cool, that's why. The prize: Enlightenment!
The officers of these ships are Eternals, mind-reading beings who exist above and beyond our universe. They've lived so long that they have no original thoughts of their own, and must read the minds of mortals ("Ephemerals") in order to alleviate their soul-crushing boredom. Having Enlightenment will ensure that they will never be bored again. The Doctor uses a viewscreen to look at another captain and notices he's wearing an out-of-period red jewel that is very important to the plot so pay attention. The ships round Venus, and Striker's ship edges so close to the planet in an attempt to get ahead that the ship's almost destroyed. Another ship comes so close that it actually is destroyed. The Doctor, as always, thinks something more sinister is at hand.
Tegan, Turlough and the Doctor go up to the deck and Turlough suddenly goes apeshit. The Black Guardian is not happy that Turlough failed to murder the Doctor, and his disembodied voice tells him he will remain on the ship forever, in "perpetual torment". Turlough shouts "NO! I WILL NEVER SERVE YOU AGAIN!" and jumps overboard.
A badly-yellowscreened net saves him and he's taken aboard another ship, led by the ruthless and hammy Captain Wrack. He manages to convince her that he's on her side and wants to share the prize, and due to his "devious" and "confused" mind Wrack has difficulty reading it. Wrack sends her first mate (played by hammy pop star Leee John) to present Captain Davey (another competitor) with a jewelled sword and to deliver party invitations to the other captains. Striker refuses the invitation, but the Doctor accepts, wanting to retrieve Turlough.
Meanwhile, Davey's ship explodes. What a coincidence! Tegan is horrified by Marriner's aloof reaction to all the "Ephemerals" who just died on that ship. She's able to shield her mind from him, anyway, simply by being extra grumpy, but it only serves to intrigue him more and he develops a creepy stalky crush on her in the process. Meanwhile, the Doctor puts two and two together and realizes that any ship that challenges Wrack's goes all explodey. On Wrack's ship, she reveals to Turlough how she does it: she goes to a vacuum-sealed chamber where she uses the Black Guardian's power to make the red jewel explode. Somehow.
The Doctor, Tegan and Marriner travel to Wrack's ship, where they mingle at a party while Turlough sneaks off to examine the chamber of explodium. He finds an eye-shaped grid (that looks amazingly like the CBS network's logo◊) open to space, but a pirate locks the door and turns off the vacuum shield. Fortunately, the Doctor finds Turlough before he suffocates, but both are immediately captured. Wrack lures Tegan away from everyone else and momentarily stops time so that she can sneak a red jewel onto the tiara Tegan is wearing for the party.
Turlough turns on the Doctor again and Tegan, the Doctor and Marriner are sent back to the ship. The Doctor doesn't mind, for he believes that Turlough is trying to stop Wrack. He's right, and Wrack realizes it: she sentences Turlough to Walk the Plank. She pauses, however, when Turlough tells her that he, too, serves the Black Guardian and decides to let him watch her destroy Striker's ship. Luckily, the Doctor realizes just in time that Tegan's tiara contains the jewel. He thwacks it to pieces with an axe, and when that only makes it stronger, he throws it overboard before Wrack can destroy it. He travels in the TARDIS to the other ship to keep her from winning but is thrown overboard along with Turlough. Wrack wins!
Or does she? Well, it turns out that she and her first mate were the ones who were thrown overboard, not the Doctor and Turlough. They, along with Tegan, Striker and Marriner go to the Enlighteners to claim their prize.
They turn out to be everyone's favourite omnipotent, extradimensional beings who wear birds on their heads now for no apparent reason: the Black and White Guardians! The Doctor declines the prize, saying that no one should receive complete enlightenment, including him.
Striker leaves, along with Marriner, after the latter gets rejected by Tegan... again. But the White Guardian turns to Turlough, and says that since he helped the Doctor win, he's entitled to a portion of Enlightenment. As he reaches out to grab Enlightenment (represented here by a huge white crystal) the Black Guardian says that since the Doctor's indebted to him, Turlough can either have Enlightenment or give up the Doctor.
Yes, he refuses Enlightenment and throws the crystal at the Black Guardian, who promptly catches fire because "light defeats darkness". The White Guardian congratulates Turlough, and the Doctor says that Enlightenment was not the diamond, but the choice. Cue credits.
This story marked the final televised appearance of the Black and White Guardians and their ducky hats, though a character intriguingly similar to the Black Guardian — though minus the hat, and identified as "the Trickster" — turns up in The Sarah Jane Adventures. The Guardians, of course, return in the Doctor Who Expanded Universe, including Big Finish Doctor Who.
- Abhorrent Admirer: Tegan is less than thrilled to be the target of Marriner's affections.
- All There in the Script: Although the dialogue in which he gives the information is inaudible, the script (or lip-reading his initial message) makes it clear that the White Guardian's mission is for the Doctor to stop Wrack winning the race, which would have devastating consequences for the whole universe.
- Anachronism Stew: In-universe; Tegan spotting scuba gear on what appears to be an Edwardian ship is the first sign that things aren't as they seem.
- Blue-and-Orange Morality: The Eternals, especially Striker and Marriner, simply do not understand human/Time Lord morality. Wrack is a bit more of a clearcut villain, but still has shades of this.
- Brainwashed: Brainwashing rum is given to the sailors to prevent them from questioning why they're on the ship and why it's in space.
- And when it turns out one of them is a teetotaler... they make him happy to continue working for them in (thankfully unspecified) other ways.
- Breaking the Fourth Wall: Wrack turns from Tegan while monologuing to directly address the camera, telling the absent Doctor he will be destroyed.
- Complete Immortality: The Eternals dwelt in the domain of Eternity rather than the smaller one of Time. This meant they were unaffected by Time and thus unaging. Another factor is that Eternals cannot be destroyed, only transferred back to Eternity. However, in the Doctor Who Magazine comic Uninvited Guest, the Seventh Doctor might have found a loophole.
- Continous Decompression: Turlough is locked in a small chamber when the protective force field is deactivated letting the air escape to space. It takes several minutes for the Doctor to find Turlough, during which time it is still slowly evacuating though the hole is quite large and the room is quite small. Ironically it is also an example of Explosive Decompression, since when Turlough is rescued, he says "I would have exploded in the vacuum of space."
- Cool Ship: The whole race idea is built on this trope. Admittedly, it is pretty awesome.
- Deceptive Disciple: Turlough
- Dissonant Serenity: Marriner, of the creepiest kind
- Distressed Dude: Turlough. This seems to snap him right out of suicidal mode. And the Doctor himself.
- Dogged Nice Guy: Marriner is definitely interested in Tegan, and seems to mean her no harm, but his Blue-and-Orange Morality is too strange for her.
- Driven to Suicide: Turlough (attempted).
- The Edwardian Era: Where the sailors were snatched from.
- Eldritch Abomination: The Eternals exist outside of time and space in eternity, have great Reality Warper powers and they are to Time Lords what Time Lords are to other races.
- Enhanced on DVD: The DVD has an optional recut which, most importantly, replaces the original model footage of the various space "ships" with new CGI. This particularly improves the notoriously bad and confusing original depiction of Turlough's suicide attempt and rescue.
- Friend or Idol Decision
- Funny Background Event: The Doctor quietly replaces his wilted lapel celery with a fresher one from Wrack's party.
- Gorgeous Period Dress: Tegan's Edwardian ballgown.
- Hidden Depths: Tegan proves capable of closing down her mind to an immortal being with tremendous psychic powers.
- Impossibly-Low Neckline: So low, in fact, that Tegan's ball dress got several letters of complaint sent to the BBC.
- Jerkass: The Doctor is really quite unfair to Tegan at several points, notably losing his patience with her for leaving the TARDIS to bring him the White Guardian's message (on the Guardian's instructions), which he had specifically asked her to intercept.
- Large Ham: The Black Guardian obviously takes the cake, but Wrack does her absolute best to match him.
- Mind-Control Eyes: The Doctor notices that the sailors "look hypnotised".
- More Than Mind Control as Mind Rape: The Eternals do this a lot, not always successfully.
- Newspaper Dating: While they're exploring the ship at the beginning of the story and trying to figure out where they are, the Doctor finds a newspaper with a 1902 cover date and the headline "First British Submarine Launched". Played with, since it turns out the Eternals have taken their crews from all through history, so the newspaper shows when Striker's crew were taken but doesn't help with the question of where and when they are now.
- No-Sell: Tegan manages to shut an immortal, eternal being out of her mind, just because he was annoying her too much.
- Nothing Is Scarier: At the beginning of the episode, the TARDIS crew has no idea where they are, and the scanner gives them no help whatsoever. Made even scarier for Tegan, since she stays there longer and is therefore in the dark for a longer time.
- One-Word Title
- Order Versus Chaos: The Guardians. With matching birds on their heads (white and black, respectively, for extra subtlety).
- Parent Service: Tegan wears a beautiful, low-cut◊ dress that actually caused a couple of Wardrobe Malfunctions.
- Pirate Girl: Captain Wrack
- Re-Cut: The DVD version includes a "movie" edit with new CGI special effects and some scenes altered or re-ordered.
- Secret Test of Character: The whole business with the Enlightenment diamond turned out to be this for Turlough.
- Shaped Like Itself: At the end of the first segment, The Doctor says "We're not on a yacht, we're on a ship", which would sound kind of silly if he hadn't continued "... a space ship!"
- Space Is an Ocean
- Space Pirates: Lynda Barron (Captain Wrack) plays one of the best space pirate captains anywhere. Her performance is larger than life, but works well within the confines of the story.
- Space Sailing: The Doctor and his companions find themselves on board a Sufficiently Advanced Alien Edwardian ship in space, powered via solar sails, which is participating in a race around the planets, along with other such ships from different periods from human history, including a Greek trireme... with rowers.
- Switching P.O.V.: Switches with the Doctor, Tegan and Turlough
- The consistent tension between Tegan and Marriner is told from both points of view: he views her as fascinating, but she sees his fascination with her as physically (and sexually) threatening, and makes her discomfort VERY clear to him (because she is Tegan, and she does not stand for that sort of behaviour). He is often shot as though he physically looms over her, driving the point home. Marriner is deeply puzzled by Tegans fear, which emphasizes his alien nature (and his Eternal privilege).
- Telepathy: The Eternals can use telepathy and create objects from the memories of Ephemerals, but their powers were not limitless and they could not read minds from great distance or from strong minds (though Adrenaline from the mind they're accessing helps greatly).
- Unwitting Pawn: Averted when Turlough turns on the Black Guardian - but also implicitly played straight with the Doctor as the gambiter and the Black Guardian as the sucker.
- Walk the Plank
- Wardrobe Malfunction: That beautiful, low-cut◊ Edwardian dress Tegan wears for the party? Incompatible with the Doctor Who tradition of running up and down corridors—Janet Fielding popped out of it a couple of times during filming.
- What Is This Thing You Call "Love"?: Marriner, who has existed for an unknowable amount of time and can read minds to boot, has never even heard of love, let alone experienced it for himself.
- Who Wants to Live Forever?: Eternity is boring, so the Eternals have to find something to do to occupy their time.
- You Have Failed Me: played straight (with ham) by the Black Guardian