The Fourth Doctor's psychological and moral struggle with the alien entity 'The Nucleus' taking control of his body and mind, forcing him to confront his own submission while maintaining outward composure

The Doctor and Leela step through the airlock of Titan Base into the rock-cut corridors, their helmets sealed and visors down. Against the sterile backdrop of the station's metal and …

The Doctor’s unraveling reaches a breaking point as Meeker’s relentless demands exploit his growing corruption. Repeating the entity’s line about the purpose being all important, Meeker torments the Doctor into …