Peter Davison returns as the fifth incarnation of the Doctor in his final season. Janet Fielding and Mark Strickson join the Doctor as companions Tegan Jovanka and Vislor Turlough. The Shape-shifting Android Companion Kamelion, played by Gerald Flood, makes his second and final appearance in 'Planet of Fire'. New companion Peri Brown played by Nicola Bryant makes her first appearance in 'Planet of Fire'. Colin Baker makes his début as the Sixth Doctor in the final story, 'The Twin Dilemma'.