Standard Definition

Originally aired on

09 May, 1964

Written by

Terry Nation

Directed by

John Gorrie

Cast List

William Hartnell - The Doctor
William Russell - Ian Chesterton
Jaqueline Hill - Barbara Wright
Carole Ann Ford - Susan Foreman
Robin Phillips - Altos
Katherina Scholfield - Sabetha
Henley Thomas - Tarron
Michael Allaby - Larn
Raf de la Torre - Senior Judge
Alan James - First Judge
Peter Stenson - Second Judge
Fiona Walker - Kala
Martin Cort - Ayden
Donald Pickering - Eyesen

Synopsis

Materialising on an island of glass in a sea of acid, the Doctor, Susan, Ian and Barbara find themselves chosen to embark on a perilous quest set by Arbitan, Keeper of the Conscience of the planet Marinus. The Conscience machine has the power to control the minds of everyone on Marinus, and it is in danger of falling into the hands of the sinister Yartek, leader of the alien Voord. To prevent disaster, the TARDIS crew must recover the machine's operating keys, hidden in various locations around the planet. Others have attempted this task before - but none have ever returned. From Morphoton to Millenius, battling ice soldiers and deadly plants, overcoming hypnotic conditioning and hostile witnesses, this trek across Marinus promises to be the four travellers' most challenging adventure yet.