The TARDIS materializes on the glassy beach of a small island surrounded by a vast sea of acid. Inside an enormous tower, the only structure on the island, is Arbitan and the giant mind control machine he is sworn to protect. Arbitan puts a force field around the TARDIS and forces the Doctor and his companions to search the planet (that being the planet they are currently on, Marinus) for the four missing keys needed to upgrade his machine. Despite all of his actions, Arbitan is one of the least evil people on the planet compared to everyone else the group encounters on their mission to recover the keys to Arbitan's machine. Each key is located in a different region of Marinus with its own corresponding danger: a city controlled by hypnotic brain creatures, a jungle full of traps and predatory plants, ice caves guarded by robot soldiers, and a vaguely fascist state where Ian is framed for murder. Oh yeah, and there's these aliens in wet suits with big, crazy helmets. Needless to say, the group have a lot on their plates.
Rating: It's a pity you don't have color television%
(Image from joe.siegler.net)