S8E5
Cynical with undercurrents of tragic irony
Written by Don Houghton
View Graph

The Mind of Evil Part 1

When the Doctor and Jo investigate a new process for treating criminals, they uncover a sinister machine that extracts evil impulses, leading to bizarre deaths and a growing menace that threatens to disrupt a World Peace Conference.

The Doctor and Jo arrive at Stangmoor Prison, disguised as a medieval castle, to observe a new treatment for criminals called the Keller process. Professor Kettering explains that the machine extracts negative impulses, leaving behind rational individuals. The first demonstration on a prisoner named Barnham results in an alarming spike in the machine's readings, though Kettering dismisses it as a minor malfunction.

Soon after, a medical student, Arthur Linwood, is found dead in the process theatre, seemingly attacked by rats despite the prison being rat-free. The Doctor suspects the Keller machine is responsible. Meanwhile, at a World Peace Conference, a Chinese delegate, Captain Chin Lee, reports that important state documents have been stolen. The Brigadier, with UNIT, investigates, suspecting the Americans, but Chin Lee's behavior seems suspicious.

Back at the prison, Kettering continues to defend the machine and its safety, but the Doctor remains unconvinced. Another death occurs: Kettering himself is found drowned in the process theatre, even though the room is dry. The Doctor discovers that Linwood had a phobia of rats, and Kettering appears to have shared trauma, now made real.

Chin Lee is revealed to have waited nearly half an hour before reporting the General's body, raising suspicions further. As the Brigadier investigates the murder of General Cheng Teik at the Peace Conference, he requests the Doctor's assistance. Meanwhile, the Governor agrees to suspend the Keller process, and the Doctor prepares to make the machine safe. He learns that Emil Keller had a Chinese assistant during the machine's installation. In the prison's medical ward, Barnham, the processed prisoner, seems fully recovered physically, but his mental state remains uncertain, and Summers admits concern, as a wave of mental instability and anxiety spreads through the prison population. The net tightens as the Doctor and UNIT piece together the clues, leading to more deaths, and more evil unleashed by the machine.


Events in This Episode

The narrative beats that drive the story

32
Act 1

The Doctor and Jo arrive at Stangmoor Prison, a formidable medieval fortress now serving as a high-security facility, to observe the controversial Keller process. Professor Kettering, the machine's ardent champion, explains its function: to extract "negative or evil impulses" from criminals, thereby transforming them into "rational, well-balanced individual[s]." The Doctor immediately voices skepticism, questioning the concept of "infallibility" and sensing an inherent "evil" in the device. The first demonstration on prisoner George Patrick Barnham proves unsettling; the machine's dial registers an unprecedented spike, and Barnham screams in agony. Kettering dismisses this as a "minor malfunction," but the Doctor remains unconvinced, declaring the machine a "menace to mankind." The narrative then introduces a parallel plotline: at a World Peace Conference, Captain Chin Lee reports the theft of crucial state documents from General Cheng Teik's suite, placing blame on "imperialist Americans." Brigadier Lethbridge-Stewart and UNIT begin their investigation, but Chin Lee's subsequent actions—secretly burning a document and touching a device behind her ear—establish her as a highly suspicious figure. The act culminates with the discovery of medical student Arthur Linwood's body in the process theatre, covered in "bites and scratches" consistent with a rat attack, despite the prison's rat-free environment. The Doctor, observing Linwood's terrified expression, immediately suspects the Keller machine, setting the central conflict in motion.

Act 2

Following Linwood's death, the Doctor's suspicions about the Keller process intensify. He learns Linwood suffered from a phobia of rats and connects the "bites and scratches" on his body to this fear, directly accusing the machine of manifesting Linwood's deepest terror. Kettering vehemently denies any connection, dismissing the Doctor's scientific credentials. Meanwhile, the Peace Conference plot escalates dramatically as General Cheng Teik is found murdered. Brigadier Lethbridge-Stewart, now dealing with a homicide, requests the Doctor's assistance, highlighting the growing severity of both situations. Back at the prison, the Keller machine begins to hum ominously. Professor Kettering, alone in the process theatre, experiences a vision of drowning and subsequently dies, his lungs full of water, in a completely dry room. The Doctor quickly deduces the machine's escalating power to affect minds and manifest phobias, demanding its immediate destruction. Governor agrees to suspend the process, allowing the Doctor to begin making it safe. The Brigadier, investigating Cheng Teik's death, exposes Chin Lee's lie about reporting the body immediately, confirming her duplicity. A critical revelation emerges: Emil Keller had an "attractive Chinese girl" assistant during the machine's installation, forging a direct, albeit mysterious, link between the prison and conference plots. The act concludes with Barnham, the first processed prisoner, appearing physically recovered but mentally hazy, while Doctor Summers confirms Kettering's inexplicable drowning, underscoring the pervasive and bizarre threat unleashed by the machine.