Doctor Who: The Ribos Operation (Part 4)

"The Ribos Operation (Part Four)" is the fourth episode of of the sixteenth series of the original British science fiction television programme, Doctor Who. It is the 492nd episode of the show overall and the fourth and final chapter in the "The Ribos Operation" storyline and features Tom Baker as the Fourth Doctor. It was directed by Michael Hayes with a script written by David Fisher. This episode aired on BBC One on Saturday, September 23rd, 1978.