In the conclusion of the four-part story "The Ribos Operation," the Doctor (
Tom Baker) and Romana (Mary Tamm) must prevent the first segment of the Key to Time from falling into the proverbial "wrong hands." Their success hinges upon the Doctor's ability to pass himself off as a minion of the fearsome Graff Vynda-K (Paul Seed) -- and to avoid being blown to bits in the process. Originally telecast on Septmeber 16 1978, "The Ribos Operation, Episode 3" was written by Robert Holmes. ~ Hal Erickson, All Movie Guide