The Doctor is trapped in a parallel world that is going up in flames. Can he escape in time to save Earth in his own universe?
Quest roles:
Nicholas Courtney(Brig. Lethbridge-Stewart), Derek Newark(Greg Sutton), Pat Gorman(Pilot), John Levene(Sergeant Benton), Philip Ryan(Primord), Sheila Dunn(Petra Williams), Dave Carter(Grierson), Olaf Pooley(Professor Stahlman), Walter Henry(Primord), Peter Thompson(Primord)