Season eighteen of Doctor Who was the last to feature Tom Baker in the lead role, and the first to be produced by John Nathan-Turner, who would continue to run the show until its cancellation. The season featured many other changes to the cast as well, as Romana and K-9 were written out and three new companions were introduced in rapid succession. The Master also finally returned as a continuing villain, with a new actor settling into the role. The season is also notable for a set of stories that have come to be known as “the E-Space Trilogy,” set in an alternate universe. More interesting facts about Time Lord history also come to light.
From “The Leisure Hive”
The Doctor bypasses the randomizer on the TARDIS navigational control to visit Brighton Beach, though he gets the century and the season wrong, as Romana informs him. K-9 is damaged when salt water gets into his systems, and Romana convinces the Doctor to take them instead to the Leisure Hive on Argolis, where they encounter a late-23rd century Earth scientist performing fraudulent tachyonics experiments. The Doctor cannibalizes the randomizer when things go wrong and leaves it on Argolis, dismissing the threat posed by the Black Guardian.
While repairing K-9, the Doctor and Romana find themselves suddenly caught in a “chronic historesis,” or time-loop, which has been created by an alien wishing to impersonate the Doctor. The alien, a Zolpha-Thuran named Meglos, wants to steal the Dodecahedron, a vastly powerful energy source on the planet Tigella, which the Doctor had visited 50 years before. Escaping from the trap, the Doctor, Romana, and K-9 continue on to Tigella, where the Doctor is arrested for Meglos’ betrayal and Romana is captured by pirates. Sorting things out, the Doctor and Romana go to Zolpha-Thura to prevent Meglos and the pirates from turning the Dodecahedron into the ultimate weapon. Due to the Doctor’s sabotage, the weapon is destroyed, along with the planet. While the Doctor is saying goodbye to the Tigellans, Romana emerges from the TARDIS and announces they’ve been summoned back to Gallifrey.
From “Full Circle”
The Doctor: Do you mind if I come in?
Romana: The Time Lords want me back.
The Doctor: Yes. Well, you only came to help with the Key to Time.
Romana: Doctor, I don’t want to spend the rest of my life on Gallifrey. After all this -- !
The Doctor: Well, you can’t fight the Time Lords, Romana.
Romana: You did… once.
The Doctor: Hmm. And lost.
Romana: Well, there’s nothing more to discuss then. We have to go.
The Doctor: I’m afraid so.
En route to Gallifrey, the TARDIS encounters a spatial anomaly, and when they materialize at the proper coordinates, they are on the wrong planet. While inspecting the controls, they hear a pounding on the door. Romana opens the door and they discover a young boy, wounded and delirious. However, he displays a rapid healing ability. Romana states that the TARDIS weighs five million kilos in the local gravity, which appears similar to Earth’s. The Doctor learns that the planet is called Alzarius, and the inhabitants are planning to travel to their home planet Teradon aboard their Starliner, though their incessant unnecessary maintenance prevents them from actually taking off, a necessary ruse since no one knows how to actually pilot the vessel. The Alzarians are terrorized by reptilian marshmen that turn out to be links in their own evolutionary chain. It is only the Starliner itself that is from Teradon, and earlier marshmen evolved rapidly to inhabit it. The Doctor programs the ship to return to Teradon with the Alzarians on board. The Doctor and Romana deduce that the spatial anomaly was a charged vacuum emboitment, or CVE, which shunted the TARDIS into the smaller universe of an exo-space/time continuum which the Doctor calls E-Space. The rarity of such an event leads them to believe they are trapped.
The Alzarian boy is named Adric, and he proudly wears his badge for mathematical excellence. He told his brother Varsh earlier that his destiny was to leave Alzarius, but not on the Starliner. He fulfills this upon meeting the Doctor. When Varsh is killed fighting the marshmen, Adric decides to stow away on board the TARDIS and remain with the Doctor and Romana. He travels out of E-Space to explore the Doctor’s universe, where he is eventually killed when the Cybermen trap him aboard a space freighter that crashes into the Earth.
From “State of Decay”
Still trapped in E-Space, the Doctor, Romana, K-9, and Adric materialize on the next inhabitable planet they find. Incredibly, they discover equipment from a crashed Earth spaceship, the Hydrax, which had also passed through a CVE a millennium earlier. Unbeknownst to them, Adric gets captured by the ship’s three crewmembers, who have survived by becoming vampires. While held prisoner, the Doctor tells Romana of a legend related to him by a hermit in the mountains of southern Gallifrey concerning a great war between the Time Lords and a race of giant vampires, each of which reportedly could suck the life out of an entire planet. The Time Lords eventually destroyed all but the king of the vampires, who disappeared without a trace. It was this war that caused the Time Lords to forsake violence forever. The Doctor says the legend was supposedly set in the misty dawn of history when even Rassilon was young. Romana says that she once worked in the Bureau of Ancient Records where she read about something called the Record of Rassilon, which told how to destroy the vampire creatures. With K-9’s help, the Doctor finds the information buried in the TARDIS storage rooms -- a collection of punch cards on a tea cart. The cards reveal that the legend is true, and also Rassilon’s instructions for defeating the monsters. The Vampire King disappeared into E-Space and has been gathering strength while the three crewmembers served his need for blood. The Doctor destroys it using the Hydrax to pierce its heart. The three human vampires then wither to dust. The Doctor tells Adric he’s taking him home.
From “Warrior’s Gate”
The TARDIS collides with a time rift and goes out of control. They are boarded by an interphasic Lion Man who lands the TARDIS at the zero point between the two universes. It is a void in which a space freighter has also been trapped for months. The Doctor follows the Lion Man to a stone arch that leads into an ancient room. Romana meets the crew of the ship and discovers they use the lion men, or Tharils, to allow them to travel through time, as the Tharils are time-sensitives who can “ride the time winds.” Believing Romana has similar powers, the captain forces her to aid them. The Doctor learns that the Tharils were once rulers of a vast empire until they were all but wiped out by their slaves, and then became themselves hunted by slavers. K-9 announces that the void is collapsing due to the extreme mass of the freighter, which is made of dwarf star alloy in order to hold the time-sensitives. Thanks to the Doctor, the slaver ship is destroyed and the Tharils escape, but Romana and K-9 remain with them in E-Space to help free the rest of the Tharil race from bondage. Romana leaves all her things aboard the TARDIS (where they are eventually lost when the Doctor must jettison her room.) Meanwhile, the TARDIS crosses back into its home universe, taking Adric along with it. The Doctor has little choice but to accept him as a traveling companion.
Romana: The TARDIS -- gone.
K-9: TARDIS preserved in concept, Mistress. This unit contains all necessary schedules for duplication of the TARDIS, Mistress.
Romana: Exactly, K-9. Biroc will help us use the gateway to travel anywhere in E-Space, and we can give him time technology.
Biroc: You shall be our Time Lord, and we will travel far. Our people are enslaved on many planets.
Romana: And you and I, K-9, are going to help Biroc free them. That’s something we’ve got to do, don’t you think?
K-9: Affirmative, Mistress.
From “The Keeper of Traken”
Traveling back in normal space, the TARDIS is intercepted by the enigmatic Keeper of Traken, a powerful being who’s reaching the end of his life. The Empire of Traken is the most harmonious empire in the history of the universe, a place the Doctor describes as “so full of goodness that evil just shriveled up and died.” The Keeper has sensed a great evil and asks the Doctor to come to Traken to help with the transition of power. However, upon arriving, the Doctor falls under suspicion by the ruling council. He finds a friend in the scientifically-minded Consul Tremas. His young wife Kassia has fallen under the influence of a malevolent statue called the Melkur. They also meet Tremas’ daughter Nyssa, who strikes up a friendship with Adric. The Melkur is really the Doctor’s old enemy, the Master, still in the warmed-over cadaver of his used-up Gallifreyan body. The statue is his disguised TARDIS. The Master assumes the power of the Keeper of Traken, but the Doctor manages to defeat him. The Master escapes, though, and is able to take over the body of Tremas, whose appearance alters to resemble the Master’s old self.
Although raised as an aristocrat on the prime world of the Traken Union, the young Nyssa requites herself well during the Melkur’s attack, showing bravery and ingenuity. The Master kills her step-mother in his bid for power. But after the new Keeper is installed and the Doctor and Adric have left, her father, Consul Tremas, mysteriously disappears. Nyssa contacts the Doctor and asks for his help, then meets a being called the Watcher, who takes her to the planet Logopolis, where she is reunited with the Doctor and Adric. It is here that she learns her father’s fate, his body commandeered by the Master, and watches as the entropy field he accidentally unleashes destroys Traken, leaving Nyssa alone and homeless. She remains with the Doctor for some time, seeing him through his regeneration. She eventually decides to remain on the death ship Terminus to help the victims of Lazar’s disease. Her subsequent fate is unknown.
Adric interrupts the Doctor pacing around in the TARDIS cloister room. He tells Adric about the cloister bell, the onboard warning system. Ruminating about entropy, the Doctor expresses dissatisfaction about the state of the ship’s systems. Wanting to avoid telling the Time Lords about Romana staying in E-Space, he decides to make a return trip to Earth to retrieve a real police box to measure it, in order to take the measurements to Logopolis for the block transfer computation process. On their way back to the console room, the cloister bell rings ominously.
Adric: So the chameleon circuit’s stuck?
The Doctor: Exactly.
Adric: In Tutter’s yard?
The Doctor: Totter’s Yard. Anyway, it doesn’t matter. It was ages ago. She was in on Gallifrey for repair when I borrowed her.
Adric: But I thought she was yours!
The Doctor: Well, on a sort of finders-keepers basis, yes. I should have waited until they’d done the chameleon conversion, but there were other pressing reasons at the time.
The TARDIS materializes around a police box, but while measuring it, the sensors detect a gravity bubble. Stepping outside to investigate, the Doctor sees a young woman changing the tire on her car, and in the distance, a ghostly white figure watching him. He appears disturbed by the specter, seeming to understand what it means. Within the police box seems to be another TARDIS and another in infinite regression. It is a trap laid by the Master, whose time capsule was inside the police box when the Doctor’s TARDIS materialized around it, causing a dimensional instability. The Doctor’s ship is grounded until he uses the architectural configuration system to jettison Romana’s room, thus giving them a boost. Once underway, the Doctor receives a transmission.
The Doctor: The message was very faint. It was from Traken.
Adric: Traken? How’s Nyssa?
The Doctor: Nyssa’s all right.
The Doctor: Vanished. The Master must have had a second TARDIS hidden away somewhere.
Adric: The Master’s escaped from Traken? But why take Nyssa’s father?
The Doctor: To renew himself. He was very near the end of his twelfth regeneration.
Adric: He’s taken over Tremas?
The Doctor: Yes.
Adric: Can a Time Lord do that?
The Doctor: Well, not just a Time Lord by himself, but with some of the powers of the keepership still lingering -- and I was so sure, I was so sure -- he must have known I was going to fix the chameleon circuit!
Adric: He read your mind?
The Doctor: He’s a Time Lord! In many ways, we have the same mind!
In a desperate attempt to purge the TARDIS, the Doctor decides to materialize underwater. However, he lands instead on a barge, from which he sees the ghostly figure again on a bridge. He goes and confers with the strange figure and then sets off immediately for Logopolis, saying he’s dipped into the future and sees imminent catastrophe. When they land, the young woman emerges from the corridors, rather distraught. She introduces herself as Tegan Jovanka. The Master then infiltrates Logopolis in order to take control of their reality-altering mathematics. Nyssa appears, claiming to have been brought by “a friend of the Doctor’s,” really the ghostly figure called the Watcher, who continues to hang around in the background. The Doctor and the Master meet and Nyssa learns that the Master has possessed her father’s body. They all learn that Logopolis is the keystone that holds the universe together, and the Master’s tampering has caused the universe to begin to unravel. To prevent entropy from collapsing the universe long ago, the Logopolitans created the charged vacuum emboitments to open the system and release some of the entropy. The Doctor and the Master collaborate to undo the damage. To escape the collapse of Logopolis, they travel aboard the Master’s TARDIS to the Pharos Project on Earth to use its radio telescope to manipulate a nearby CVE, thereby restabilizing the system. Meanwhile, aboard the Doctor’s TARDIS, the Watcher has taken them outside space and time, where Adric and Nyssa can observe the spreading effect of the entropy field. To her horror, Nyssa sees Traken extinguished. They return into the space-time continuum, materializing at the base of the Pharos Project radio telescope. The Master double-crosses the Doctor, intending to set himself up as the ruler of the universe. They scuffle atop the radio telescope, and foiling the Master’s scheme causes the Doctor to plummet from the tower. His body shattered, the Doctor tells Adric, Nyssa, and Tegan that the end has come. The Watcher merges into the Doctor’s body, inducing a regeneration.
On February 28, 1981, Tegan Jovanka was on her way to her first day as an air hostess when she stumbled into the TARDIS while trying to phone a policeman for assistance with her Aunt Vanessa’s car. She soon gets lost in the winding corridors. While she’s inside, the Master kills Aunt Vanessa with his tissue-compression eliminator. The TARDIS travels to Logopolis before the Doctor is even aware she’s on board. For a time, Tegan wishes only to get back to Heathrow Airport to start her job, but she is prevented by various circumstances. She comes to enjoy the adventures, even though her mind becomes invaded by the psionic creature called the Mara, and decides to remain with the Doctor. However, she is left behind at Heathrow at one point. She loses her job after all, and seeming depressed, cuts her hair short and goes to visit her cousin in Amsterdam, where she crosses paths with the Doctor again. They travel together for a few years, until she becomes disgusted by the carnage left by the Daleks and parts ways with the Doctor tearfully. It seems likely Tegan would have a hard time settling back into a normal life, although the alien cultures she encountered might aid her in achieving her dream of becoming a fashion designer.