In the fifth episode of the six-part story "The Chase," the Doctor (William Hartnell) and his companions encounter terror in the jungles of the planet Mechanus, as the Daleks close in on the TARDIS. Crucial to the plotline is a master plan to replace the Doctor and his friends with robotic duplicates. Captured by the Mechanoids and thrown into prison, the TARDIS crew encounters an unexpected ally. Written by Terry Nation, "The Death of Dr. Who" was originally telecast June 19, 1965. ~ Hal Erickson, Rovi