The final segment of the Key to Time is at the heart of a devastating war between neighbouring planets Atrios and Zeos. The Fourth Doctor discovers that a sinister entity is manipulating events and the cost of obtaining the final segment may be more personal than he imagined.
Tom Baker
as The Doctor
Mary Tamm
as Romana
John Leeson
as K-9 (voice)
John Woodvine
as Marshal
Lalla Ward
as Princess Astra
Davyd Harries
as Shapp
Ian Saynor
as Merak
Ian Liston
as 'Hero'
Susan Skipper
as 'Heroine'
John Cannon
as Guard
Iain Armstrong
as Technician
Pat Gorman
as Pilot
