Arriving on Space Station Nerva in its distant past, the Doctor, Sarah and Harry find its crew threatened by a mysterious plague. Discovering that things are not as they seem, they uncover a Cyberman plot to destroy Voga, planet of gold.
Tom Baker
Elisabeth Sladen
Ian Marter
Ronald Leigh-Hunt
William Marlowe
Kevin Stoney
David Collings
Alec Wallis
Michael Wisher
Christopher Robbie
Melville Jones
Brian Grellis