S4E22
Tragic (with undertones of grim hope)
Written by Geoffrey Orme
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The Underwater Menace Part 4

When the Doctor and his companions arrive in Atlantis, they discover a mad scientist, Zaroff, plans to destroy the world; The Doctor must undermine Zaroff's scheme or all will die.

Following directly from the previous episode, the Doctor and his companions Ben, Polly, and Jamie find themselves in the underwater city of Atlantis where they uncover a plot by the scientist Zaroff to destroy the world. Zaroff plans to detonate a bomb that will destroy the Earth. The Doctor and his companions split up. Polly and Jamie are captured by Zaroff's people, while the Doctor and Ben encounter a wounded Atlantian governor named Thous, a dissenter against Zaroff's rule.

The Doctor learns that Zaroff is exploiting a workforce of "fish people" to power his plans. He decides the only way to stop Zaroff is to flood the lower levels of Atlantis, disrupting Zaroff's operations. The Doctor tasks Sean and Jacko with warning the population and getting them to higher ground, while he and Ben head for the generating station. En route, they encounter an armed guard, Ben tricks the guard to gain access, and they knock out an engineer. The Doctor tampers with the controls to cause a power surge that would destabilize Zaroff's base of operations.

Meanwhile, Polly and Jamie escape and try to find their way back to the Doctor. Polly and Jamie realize they are below Zaroff's power source. They find a tunnel as the water breaks into Zaroff's laboratory, and quickly try to find higher ground. They eventually connect with Sean, Jacko, Thous, and Damon, as they guide refugees to safety. The Doctor and Ben reach Zaroff's laboratory, where Zaroff reveals that his plan is already in advanced stages. They try to convince Zaroff's technicians that they are in danger, but Zaroff cuts himself off from the rest of the room via a portcullis. Still, the technicians flee in panic, seeing the flood begin to overwhelm the lab. They work together to trap Zaroff behind the portcullis.

The Doctor is reluctant to leave Zaroff to drown, but Ben urges him to escape. Polly and Jamie find their way out of the tunnels, eventually reuniting with the Doctor and Ben on a mountainside. Atlantis is flooded, Zaroff presumably dies in his laboratory, and Thous envisions a new Atlantis free from the mad science. The Doctor, Ben, Polly, and Jamie depart in the TARDIS.


Events in This Episode

The narrative beats that drive the story

28
Act 1

The Doctor and Ben discover Governor Thous, wounded and a dissenter against Zaroff's destructive plans. The Doctor quickly formulates a daring strategy to stop Zaroff: flood the lower levels of Atlantis, including Zaroff's laboratory and the temple, by destabilizing the generating station. He tasks Sean and Jacko with evacuating the population to higher ground, while he and Ben embark on the dangerous mission to infiltrate the power source. They cleverly bypass armed guards, with Ben improvising a cover story to gain entry. Inside the generating station, Ben disables an engineer, and the Doctor manipulates the controls, initiating a power surge designed to break the sea walls and flood the city. Simultaneously, Polly and Jamie, separated from the main group, navigate the treacherous tunnels, realizing they are directly beneath Zaroff's power source and sensing the impending catastrophe as the vibrations intensify and the walls begin to crumble, signaling the start of the Doctor's desperate plan.

Act 2

The Doctor's plan unleashes chaos as the sea breaks into Atlantis, rapidly flooding the lower city levels and disrupting Zaroff's operations. Zaroff, increasingly frantic, struggles with power fluctuations and worker desertions, pushing his detonation schedule forward. Sean, Jacko, Thous, and Damon guide terrified refugees through the rising waters, witnessing the destruction of ancient idols and the city's infrastructure. Meanwhile, Polly and Jamie, trapped in a dead-end tunnel, desperately search for an escape route as the water level rises around them. The Doctor and Ben confront Zaroff in his laboratory, where the Doctor exposes Zaroff's true, world-destroying intentions to his technicians. The technicians, realizing their peril, flee in panic. Zaroff, in a final act of defiance, lowers a portcullis, trapping himself with his control panel. The Doctor and Ben work together to ensure Zaroff remains cut off, preventing him from activating his bomb, even as the flood begins to overwhelm the laboratory.

Act 3

With Zaroff trapped and the laboratory flooding, the Doctor expresses reluctance to abandon him, but Ben insists they escape the rising waters. They navigate the treacherous, water-filled tunnels, narrowly avoiding being cut off. Simultaneously, Polly and Jamie, after a harrowing climb through a small opening, emerge onto a mountainside, escaping the immediate danger. Back in the laboratory, Zaroff, waist-deep in water, frantically attempts to reach his detonation plunger until the rising tide engulfs him. Above the flooded city, Damon and Thous, now safe in a mountain cave with other refugees, reflect on the destruction of old Atlantis and envision a new future free from superstition and mad science. The Doctor, Ben, Polly, and Jamie eventually reunite on the mountainside, relieved to find each other alive. They board the TARDIS, and as Sean and Jacko watch in disbelief, the police box dematerializes. Inside, the companions banter, but the Doctor's attempt to 'control' the TARDIS backfires, sending them hurtling out of control into their next adventure.