The TARDIS materialises in a dank cavern, and when the Doctor and Alison emerge, they immediately fall victim to a force which causes them to relive old memories with strong emotional resonance. The Master realises what’s happening, opens up the doors and calls out to the Doctor, who manages to fight his way free of the illusions and return to the TARDIS. The cave is the home of an intangible force like a psychic vampire, which is still feeding off Alison’s emotions. When the Doctor taps into the psionic resonance of the cavern, he finds that Alison is somehow reliving some of the Master’s memories, and realises that the dormant vampire was woken by the arrival of the Master, whose mind contains memories of evil greater than anything the vampire had ever encountered before. The Doctor switches off the Master, but this only causes the vampire to redouble its efforts to drain the life out of Alison. The Doctor thus connects the Master’s android body to the TARDIS’ telepathic circuits, feeding the vampire such a surge of hatred and evil that the entity explodes into nothingness. Alison is saved, but realises that the Doctor did not hesitate to switch off the Master when he felt it necessary. What will he do to Alison if he believes that it’s necessary?