Fabula
Season 8 · Episode 10
S8E10
Tragic yet Hopeful
Written by Don Houghton
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The Mind of Evil Part 6

The Doctor and UNIT must stop the Master from launching a nerve gas missile at London, while also dealing with the escaped Keller Machine, which feeds on evil impulses and is now even more dangerous.

Following the events at Stangmoor Prison, the Doctor, Jo, and the Brigadier find themselves in a race against time to thwart the Master's latest scheme. The Master has acquired a Thunderbolt missile filled with nerve gas and plans to launch it at London, triggering a global conflict that he intends to exploit. Meanwhile, the Keller Machine, a device designed to extract evil impulses from the mind, has escaped and is wreaking havoc, leaving death in its wake.

The Brigadier and UNIT mobilize to locate and secure the missile at a deserted airfield. Captain Yates, though injured, provides crucial intelligence about the Master's plan. The Doctor seeks to understand the Keller Machine and find a way to stop it. He discovers that Barnham, the last subject of the Keller process, now possessing the mind of a child and devoid of evil impulses, acts as a neutralizer to the machine's power.

As the Brigadier prepares to attack the airfield, the Doctor realizes the danger of a direct assault and the potential for the Master to launch the missile. He convinces the Brigadier to call off the attack, proposing a risky plan to trade the dematerialization circuit from the Master's TARDIS for the missile. The Doctor uses Barnham's unique ability to contain the Keller Machine, keeping it at bay within the prison.

Jo and Doctor Summers help the Doctor protect Barnham and keep the machine contained, while the Doctor bargains with the Master. He ventures to the airfield, taking Barnham and the Keller Machine with him, while UNIT lies in wait. The exchange goes awry when the Master attempts to double-cross the Doctor. A struggle ensues, and the Doctor triggers the launch abort mechanism, however it is disabled by the Master.

In a desperate move, the Brigadier orders the missile destroyed remotely. Barnham sacrifices himself to stop the rampaging Master by disrupting the Keller Machine’s power, allowing the Doctor and Jo time to escape. The missile is destroyed, along with the Master’s location and Barnham. Though they are rid of the missile and the machine, the Master escapes in his TARDIS, vowing revenge. The Doctor is left lamenting the Master's continued freedom and his own forced exile on Earth.


Events in This Episode

The narrative beats that drive the story

50
Act 1

UNIT arrives at Stangmoor Prison following the previous confrontation, finding Mailer dead but the Master and the nerve gas missile gone. The Brigadier establishes a mobile headquarters, prioritizing the missile's recovery. Jo Grant discovers Barnham, the last subject of the Keller process, now childlike and vulnerable. Captain Yates, injured but resourceful, contacts UNIT, providing the critical location of the Master and the Thunderbolt missile at a deserted airfield. This intelligence shifts UNIT's focus to a direct assault. Simultaneously, the Keller Machine, previously contained, breaks free from its control collar, demonstrating increased power and immediately killing two prison officers. The Doctor, investigating the machine's escape, discovers Barnham's unique ability to neutralize its evil impulses, realizing Barnham acts as a living shield against the entity. This revelation provides a crucial, albeit temporary, method of containment for the rampaging machine, setting up the Doctor's immediate challenge: containing the Keller Machine while UNIT prepares to confront the Master.

Act 2

The Doctor attempts to devise a method to destroy the Keller Machine, but its resilience proves formidable. During this, Doctor Summers inadvertently triggers the machine's aggression by attempting to remove Barnham, confirming Barnham's essential role in containing it. The Master contacts Acting Governor Benton, demanding to speak with the Doctor. The Master reveals his intention to launch the nerve gas missile at London, aiming to trigger a global conflict for his own gain. The Doctor counters by revealing he possesses the dematerialization circuit from the Master's TARDIS, proposing a high-stakes exchange: the circuit for the missile. The Master agrees to the deal, but insists the Doctor come alone to the airfield, threatening immediate missile launch if UNIT interferes. The Doctor immediately contacts the Brigadier, ordering him to cancel the planned attack. However, the Brigadier, distrusting the Master, secretly instructs Major Cosworth to prepare for remote missile destruction, creating a dangerous double-cross scenario that puts the Doctor's plan and life at risk. The Doctor, unaware of the Brigadier's contingency, prepares to confront the Master with Barnham and the contained Keller Machine.

Act 3

The Doctor, accompanied by Jo, Barnham, and the contained Keller Machine, arrives at the airfield in a Black Maria for the exchange. The Master, armed, attempts to double-cross the Doctor, aiming to take the circuit and launch the missile. The Doctor disarms the Master, and Jo radios UNIT for abort instructions. The Doctor quickly re-enables the missile's abort mechanism, but the Master, having previously disabled it, prevents the launch abort. As the Doctor, Jo, and Barnham attempt to escape to a waiting helicopter, Barnham, in a selfless act, disrupts the Keller Machine's influence, allowing the Master to regain control. The Master then runs over Barnham in the van, making his escape. The Brigadier, receiving confirmation of the failed abort and the Master's treachery, orders the remote destruction of the missile. The missile, hangar, and Keller Machine are destroyed in a massive explosion, presumably killing Barnham. The Master, having recovered his dematerialization circuit during the struggle, contacts the Doctor from his TARDIS, confirming his escape and vowing future revenge. The Doctor is left lamenting Barnham's sacrifice, the Master's continued freedom, and his own forced exile on Earth.