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
as The Doctor
Patrick Troughton
as The Doctor
William Hartnell
as The Doctor
Katy Manning
as Jo Grant
Nicholas Courtney
as Brigadier Lethbridge-Stewart
John Levene
as Sergeant Benton
Stephen Thorne
as Omega
Rex Robinson
as Doctor Tyler
Roy Purcell
as President of the Council
Laurie Webb
as Mr. Ollis
Clyde Pollitt
as Chancellor
Graham Leaman
as Time Lord
