Doctor Who: Logopolis, Episode 1 (1981)

Synopsis
The Doctor (Tom Baker) endeavors to make some necessary repairs on the TARDIS' chameleon circuit by returning to London in the year 1981. Lurking somewhere in the shadows is the Doctor's old nemesis, the Master (Anthony Ainley), whose current scheme involves the total breakdown of the Universe's structure. Janet Fielding joins the cast as Tegan. The final adventure of Doctor Who's 18th season, "Logopolis" was written by Christopher H. Bidmead and lasted four episodes, the first of which aired on February 28, 1981. ~ Hal Erickson, All Movie Guide