Visits Stangmoor Prison to investigate the Keller Machine. Suspicious after linked deaths, he is captured and weakened by the Master using the machine. Later helps contain its alien mind parasite, orchestrates the Master's defeat by unleashing the parasite via Barnham, destroys the machine and missile, and remains exiled on Earth.
The Doctor investigates the controversial criminal treatment method overseen by Kettering.
Long-standing rivals with a history of imprisonment and direct physical confrontations.
Trusted allies coordinating security and investigation efforts across different locations.
The Doctor frees Chin Lee from mental control, gaining crucial intelligence about the Master.
Yates provides critical intelligence to the Doctor and UNIT to help locate the stolen missile.
Explore the full interactive character relationship map of Doctor Who: The Mind of Evil