While trying to take Turlough (Mark Strickson) to his home planet of Trion, the Doctor (Peter Davison) is unable to prevent the TARDIS from being drawn to the volcanic planet Sarn. This phenomenon is no accident -- in fact, it has been engineered by one of the Doctor's oldest and most malevolent adversaries. Nicola Bryant makes her first series appearance as Earth girl Perpugilliam "Peri" Brown, who sets the plot in motion while trying to sell an ancient artifact (actually an alien beacon), and whom Turlough has taken along for the ride on the TARDIS. Beginning its four-episode run on February 23, 1984, "Planet of Fire" was written by Peter Grimwade. ~ Hal Erickson, All Movie Guide