Time itself is in peril! The Time Lords and UNIT find themselves besieged by a mythic figure from the Time Lords' past hell-bent on destruction. The only way to defeat him is to break the First Law of Time and let the Doctor help himself — literally...
Jon Pertwee
Patrick Troughton
William Hartnell
Katy Manning
Nicholas Courtney
John Levene
Stephen Thorne
Rex Robinson
Roy Purcell
Laurie Webb
Clyde Pollitt
Graham Leaman
Patricia Prior
Denys Palmer