Place of Origin: Marinus
A humanoid species, spread across many widely differing districts, who reached the peak of technological development two thousand years before the Doctor's visit. The Marinusians built a powerful device known as the Conscience of Marinus; originally an impartial judge and jury but later upgraded into a behaviour modifier that eliminated all evil thoughts throughout Marinus. Housed on an island with glass beaches in an acid sea, the device was thought safe.
However the evil Voord overcame this pacification and repeatedly attempted to gain mastery over the Conscience and thus control the minds of every Marinusian. To counteract this threat, Arbitan, the devices guardian, scattered four of it's five microcircuit control keys throughout Marinus.
Forced to collect the keys, the Doctor and his companions visited several locations, and encountered some of the races of the planet. They first travelled to Morphoton, a sensuous decadent city populated by unblinking servants where every desire could be granted.
Second on the itinery was a fiendishly booby-trapped building surrounded by aggressive plantlife, where nature's tempo of destruction was accelerated following ill-advised scientific experiments. Next was a frozen wasteland of forests, mountains and scattered villages populated by wolves, ruthless fur trappers and sinister frozen ice soldiers.
The final destination was the city of Millenius, home to a highly civilised society led by elders and policed by the guardians. Alas not all facets of Millenius' society was enlightened, for example their legal system was based on the presumption that the accused was considered guilty unless he/she could prove otherwise. Sentences varied from a stint in the desert glass factories to execution.
Appearances:
The Keys of Marinus