In the third episode of the four-part story "Planet of Fire," the Doctor (Peter Davison) tries to elude the clutches of his old adversary, the Master (Anthony Ainley), who has taken on a formidable henchman, the shape-shifting Kamelion. Meanwhile, Turlough (Mark Strickson) makes several startling discoveries about his home planet Trion. Written by Peter Grimwade, "Planet of Fire, Episode 3" first aired on March 1, 1984. ~ Hal Erickson, All Movie Guide