The Keys of Marinus
Written by Terry Nation and directed by John Gorrie , the serial takes on a "mini-adventures" format , in which the First Doctor ( William Hartnell ) , his granddaughter Susan Foreman ( Carole Ann Ford ) , and her teachers Ian Chesterton ( William Russell ) and Barbara Wright ( Jacqueline Hill ) search for five keys to restore the Conscience of Marinus , a computer which maintains law and order . 
<triplet> First Doctor <subj> William Hartnell <obj> performer <triplet> Susan Foreman <subj> Carole Ann Ford <obj> performer