AllMovie

Doctor Who's incredibly brief seventh series concluded with its fourth adventure, "Inferno." Written by Don Houghton, this story arc lasted seven episodes, the first of which aired May 9, 1970. The titular Inferno is a government project dedicated to drilling into the center of the earth in search of new energy resources. In the course of investigating a sticky substance found at the earth's core, the Doctor (Jon Pertwee) is thrust into an alternative reality -- though of course, all of this is still ahead of him in Episode One.