New companion, old villain, and a Master plan so small it almost fits in your pocket.
Short Synopsis
The Doctor and Turlough pick up Peri in 1980s Lanzarote, then immediately drag her to the volcanic planet Sarn. There, they uncover a cult, some dodgy prophecies, and — surprise! — a pocket-sized Master trying to restore himself. Turlough finally gets closure, Peri gets recruited, and the Master gets barbecued.
Extended Storyline
We open not in outer space but in Lanzarote, where Perpugilliam “Peri” Brown is attempting to avoid an awkward holiday with her overbearing stepfather Howard. Peri is armed with an American accent, teenage sulkiness, and enough swimsuits to make the BBC’s marketing team very happy. She promptly stumbles into the Doctor’s orbit when Turlough rescues her from drowning. Naturally, she ends up tagging along in the TARDIS before she’s even dried off.
Meanwhile, the Doctor has received a distress signal from Kamelion — yes, that robot companion you forgot existed because the show kept forgetting too. Kamelion is under the mental influence of… the Master! Except, the Master is currently about six inches tall, thanks to a mishap with his Tissue Compression Eliminator (a weapon that usually shrinks other people). Cue tiny Master figurine barking orders like a demonic Ken doll.
The TARDIS lands on Sarn, a planet of volcanic activity and fire-obsessed cultists who follow prophecies about “the Outsider.” It turns out these prophecies are uncannily accurate, probably because they were seeded by Turlough’s people — the Trion race — who used Sarn as a prison colony. Cue Turlough realizing his mysterious backstory is about to come crashing down on him like a falling lava flow.
The Master, still fun-sized but no less egomaniacal, uses Kamelion to manipulate the Sarn cult and maneuver the Doctor into helping him. His plan: harness the planet’s volcanic energy to restore himself to full size. Honestly, it’s impressive. Most people would panic if they were six inches tall, but the Master still finds time to scheme, posture, and attempt galactic domination.
Peri, meanwhile, is trying to figure out why she’s suddenly on an alien world and whether this whole “travelling in a blue police box” thing is really worth it. But she throws herself into the adventure and shows enough bravery (and sass) to convince the Doctor she’s companion material.
Turlough, however, is the real emotional core of the story. He discovers that his younger brother is among the colonists, learns that the Trions were responsible for Sarn’s “prophecies,” and finally decides to stop running from his past. In a surprisingly mature move, he chooses to return home to help rebuild his people — marking his official farewell.
As for the Master? His plan almost works. He uses Kamelion to regain some control, manipulates the Doctor into helping him, and comes close to restoring his full size. But, in true Master fashion, it all goes horribly wrong. He ends up trapped in the flames of an erupting volcano, screaming for the Doctor’s help as lava consumes him. The Doctor refuses, forcing viewers to wonder if this was justice, mercy, or just Davison’s Doctor finally hitting his limit with this guy. (Spoiler: the Master survives anyway. He always does. He probably keeps a punch card for death escapes.)
In the end, Turlough goes home, Peri officially joins Team TARDIS, and the Doctor leaves Sarn smoldering in his wake.