Writers: Rona Munro and Andrew Cartmel
Director: Alan Wareing
Producer: John Nathan Turner
Companion: Ace (Sophia Aldred)
No. of Episodes: 3
Summary: The Doctor and Ace return to Perivale, and Ace discovers no one remembers her and all of her friends are gone. A mysterious race of aliens that are half-cheetah, half human are attacking people. The Doctor and Ace discover that they are in league with the Master. But the Master has changed. He has become like these creatures, so savage that he is no longer himself. And the same thing happens to everyone they come in contact with.