Doctor Who: The Keys Of Marinus stars William Hartnell, the first Doctor, and is the DVD of the six part adventure released originally in 1964.
When the power of the Conscience Machine threatens to fall in to the wrong hands, The Doctor and his companions are assigned a dangerous mission by Arbitan, leader of the planet Marinus and Keeper of the Conscience Machine, to find the machine's operating keys, which are scattered around the planet. Others have attempted this, none have returned.