Doctor Who: The Keys of Marinus

An immense machine-the Conscience of Marinus-can remove evil from the minds of an entire population. The Doctor (William Hartnell) and his companions including Barbara (Jacqueline Hill) and Ian (William Russell) must undertake a deadly quest to save an island nation from a vicious attack by the evil Voord. Digitally remastered picture and sound quality. Extras include audio commentaries and interviews.

The TARDIS arrives on the planet Marinus on an island of glass surrounded by a sea of acid. The travellers are forced by the elderly Arbitan to retrieve four of the five operating keys to a machine called the Conscience of Marinus, of which he is the keeper. These have been hidden in different locations around the planet to prevent them falling into the hands of the evil Yartek and his Voord warriors, who plan to seize the machine and use its originally benevolent mind-influencing power for their own sinister purposes.
Now the machine has been modified to overcome the Voords and can be reactivated, so the keys must be recovered. In their quest, the travellers - transported from place to place by Arbitan's wristwatch-like travel dials - have adventures in the city of Morphoton; in a building besieged by ambulatory plants; with a lecherous and murderous trapper; and in the city of Millennius where Ian is falsely accused of murder and discovers that the legal rule is 'guilty until proven innocent'.
The keys are eventually retrieved and the travellers return to the island. Arbitan has been killed by Yartek, who apparently tricks Ian into handing over the final key. Ian, however, passes a fake key instead and when Yartek tries to use it the machine explodes, killing him and the Voords.

Directed by John Gorrie
Written by Terry Nation
Produced by Verity Lambert
Original Music by Ron Grainer and the BBC Radiophonic Workshop, arranged by Delia Derbyshire
Costume Design by Daphne Dare

The Voords wear clichéd but surprisingly effective wet-suit costumes, with cleverly-designed rubber masks bearing - except in Yartek's case - antennae of various different shapes.

There is a surprisingly adult scene in which the burly trapper Vasor tries to rape Barbara.

The Doctor does not appear in either the third or the fourth episode as William Hartnell was on holiday in the weeks when they were recorded.

The TARDIS arrives and leaves without the engine sound being heard outside the ship.

Darrius, the friend of Arbitan's whom the travellers meet in
The Screaming Jungle, is never referred to by name in the story's dialogue; his name is given only in the closing credits.