In the conclusion of the six-part story "Frontier in Space," the Doctor (Jon Pertwee) attempts to rescue Jo (Katy Manning) from the clutches of the Master (Roger Delgado), who has been trying to foment a war between the Earth and Draconia. In a surprise twist, it turns out that the Master is not the true villain of the piece -- a revelation which neatly segues into the series' next story arc, "Planet of the Daleks." David Maloney directed the final scene in this episode, without credit. Written by Malcolm Hulke, "Frontier in Space, Episode 6" originally aired on March 31, 1973. This program marked the final appearance of Roger Delgado as the Master; the actor was killed in a car crash shortly after wrapping up production. ~ Hal Erickson, Rovi