The Doctor (Patrick Troughton), Jamie and Zoe are captured and witness a series of war games staged by aliens on a mysterious planet, with warriors from history pitted against each other. They discover this to be a plot by the War Lords, who are being aided and abetted by the War Chief, a member of the Doctor's own race. In desperation the Doctor summons his people, the Time Lords, for help. This was Patrick Troughton's last regular appearance as the Doctor, and is the first story to feature the Time Lords.