Doctor Who: The Keys of Marinus (Story 5)

On a remote island of glass surrounded by a sea of acid, there is a machine that can remove evil from the minds of an entire population – the Conscience of Marinus. Fearful of its immense power falling into thewrong hands, its sole guardian has scattered the machine's operating keys across the planet. The TARDIS crew arrives to find the island underattack by the evil Voord. Marinus' last line of defense – and its only hope – is the Conscience machine. The Doctor and his companions must undertake a deadly quest to recover the keys of Marinus.

Originally broadcast in 1964, The Keys of Marinus is a six-episode arc that features the doctor's original traveling companions, science teacher Ian Chesterton, history teacher Barbara Wright, and the doctor's granddaughter, Susan, who is given to screaming at the first sign of peril. Hartnell's doctor is a sprightly curmudgeon who relishes adventure and mystery, which he finds after the group lands on Marinus, an island of glass surrounded by a sea of acid. Doctor and company are compelled to retrieve four microcircuits that are the keys to the Conscience of Marinus, a computer that has eliminated evil from the minds of men (except apparently the evil Yartek and his web-suited Voords, who want to seize the machine). Their quest takes them most memorably to "a planet of the most contented people" (beware the brainwashing powers of the "mesmerent"), another world overrun by plants, and finally a city where Chesterton, framed for murder, is considered guilty until proven innocent--by the doctor, of course. As is characteristic of this series, the special effects are a hokey hoot and the actors sometimes step on each others' lines. Hartnell vacationed during production and is absent for two episodes. But this is a surprisingly prophetic cautionary tale: it may be good to heed the doctor's prescient observation that "man was not made to be controlled by machines." If you have yet to make an appointment with the doctor, perhaps the episodes featuring Tom Baker--the fourth and most popular of the doctors--are a more accessible introduction. --Donald Liebenson