On his first journey in the TARDIS, young Jamie McCrimmon is taken by the Doctor, along with Ben and Polly, to a seemingly deserted volcanic island. The only things that date it are fragments of recently made Mediterranean pottery and a bracelet made for the 1968 Mexico City Olympics. All four are captured and taken in a lift down a very deep shaft that leads well below the seabed. The pressure changes render them all unconscious.
When they awake from the shock of the pressure change they find they are prisoners of humans dressed in primitive robes and bearing tridents. Yet these captors seem to mean little harm and they herd the travelers into another room where a large spread has been prepared. The High Priest of the civilisation, Lolem, introduces himself and declares they are all visitors whose presence had been foretold by the goddess Amdo. In fact they have been expected as sacrifices, and are taken away to the Temple of Amdo to be fed to a pool of sharks. The four travellers are close to a watery end when Professor Zaroff arrives. He is a renegade scientist who devised the technology from which the plankton food has been refined. The Doctor recognised his handiwork and ensured a message was conveyed to Zaroff, and the Doctor now succeeds in persuading the Professor to hire him for his scientific staff. They are all in the lost city of Atlantis - but Zaroff has a plan to raise it from the sea.
At the same time Jamie and Ben are sent to work in a mine, while Polly is marked out for conversion through surgery into a Fish Person, one of a band of genetically and surgically altered amphibians that farm the plankton for the city. Zaroff’s assistant, Damon, advances on her with a menacing syringe.
The Doctor interrupts the electricity supply, thereby distracting Damon and postponing the conversion operation. Damon blames Zaroff, revealing they have a very rocky relationship, especially considering Zaroff’s paranoia and arrogance. The crazed scientist is obsessed with his plan to raise Atlantis from the sea, planning to drain the sea away into the Earth’s core as a means to restore the land mass to the surface. The Doctor deduces such a plan will generate vast amounts of steam which will crack the Earth’s core and destroy the planet. Zaroff acknowledges this outcome is his ultimate aim. Damon has meanwhile returned to his lab to find Polly has been freed by a servant girl named Ara, and reports this to Zaroff and the Doctor. The Doctor is scandalised when he learns the fate planned for his companion, and creates a ruse to make his own escape from the laboratory.
Ben and Jamie have been placed to work in a mine where they meet two ship wrecked sailors similarly confined, Sean and Jacko. All four escape using a secret mine shaft and follow the treacherous shaft until it emerges in a temple of Amdo – the very same temple in which Polly has been hiding. Ara is still protecting them, providing food and hiding them from the guards.
The Doctor has meanwhile made contact with a priest named Ramo who is one of the most resistant to the influence being displayed by Zaroff at the Atlantean court, and warns him that Zaroff really means to destroy Atlantis. Ramo kits the Doctor in priestly robes to smuggle him before Thous, King of Atlantis, so that he can voice his warning. The King, however, is a great believer in Zaroff and says he must think about the evidence that has been presented. When he next summons the Doctor and Ramo to his court it is to hand them over as prisoners to Zaroff.
The Doctor and Ramo are taken for execution at the Temple of Amdo where Lolem is given the opportunity to make another sacrifice. However, a ruse by Polly and the others convinces the priests that a statue of Amdo has found voice. The Doctor and Ramo are spirited away into a secret room behind the statue while Lolem believes his god has swallowed the offering. When Lolem reports this miracle at court Zaroff denounces it, insulting Amdo and sowing seeds of doubt in the mind of King Thous.
The Doctor decides to cause a revolution by creating a food shortage. He realises the plankton-based food will not last long before perishing, so decides to cause its farmers to stop supply. Sean and Jacko are sent to persuade the Fish People to revolt. They succeed in causing a production strike relatively easily.
The Doctor and his friends head off to tackle Zaroff himself. The Doctor disguises himself as a gypsy soothsayer at the Atlantean market and helps trigger a ruse to separate Zaroff from his guards. Zaroff is captured by the Doctor’s party and taken to the secret room behind the statue, where the crazed man boasts his plan is unstoppable. Having faked a seizure, Zaroff manages to get hold of a trident and stabs Ramo, who has been left to guard him. Ramo survives, but is badly wounded, while Zaroff escapes. The megalomaniac has found his loyal guards and returns to the royal court mob handed, where he confronts Thous. The King is aggrieved by the strike among the Fish People and has lost his faith in Zaroff to raise Atlantis from the sea. Zaroff responds by shooting Thous, while his guards take on the royal protectors in pitched combat. In Zaroff’s own words, “Nothing in the world can stop me now.”
With Zaroff gone, the Doctor finds Thouss bleeding but alive in the throne room and has him taken to the secret chamber for safety. He then determines to flood the lower portion of Atlantis so that the reactor and Zaroff’s laboratory are destroyed. Sean and Jacko are told to alert the Atlantean populace to flee to the higher levels, while the Doctor and Ben head to the generator station to put the plan in motion. Once there they cut through cables to render the reactor unstable. All over the lower portions of Atlantis the sea walls start to perish. Jamie and Polly are caught in the flow but succeed in swimming to safety. Sean, Jacko, Thous and a pentinent Damon are also fleeing the lower reaches of the city, though Lolem is missing, presumed dead.
Zaroff has now become totally mad, obsessed with his scheme to destroy the Earth. Ben and the Doctor confront him and, with the city in ruins, his guards and technicians all flee. With the water level in Zaroff’s lab rising, Ben succeeds in trapping the madman behind a grille to prevent him reaching the detonation controls. Zaroff drowns while the Doctor and Ben flee, unable to help him.
After a long slog they make it to the surface and are there reunited with Jamie and Polly. Knowing that some of the Atlanteans, including Thous, Sean and Jacko, will have survived, the quartet return to the TARDIS and the Doctor operates the controls. They are only just taking off, however, when an external force seizes the craft hurls them uncontrollably around the console room.
Doctor Patrick Troughton (Second Doctor)
Companions Anneke Wills (Polly)
Michael Craze (Ben Jackson)
Frazer Hines (Jamie McCrimmon)
Joseph Furst — Zaroff
Colin Jeavons — Damon
Noel Johnson — King Thous
Tom Watson — Ramo
Peter Stephens — Lolem
Gerald Taylor — Damon's Assistant
Catherine Howe — Ara
P.G. Stephens — Sean
Paul Anil — Jacko
Roma Woodnutt — Nola
Graham Ashley — Overseer
Tony Handy — Zaroff's Guard
Writer Geoffrey Orme
Director Julia Smith
Script editor Gerry Davis
Producer Innes Lloyd
Executive producer(s) None
Production code GG
Series Season 4
Length 4 episodes, 25 minutes each
Episode(s) missing 3 episodes (1, 2, and 4)
Originally broadcast January 14–February 4, 1967