(He offers his hand.) (She falls to her knees.) (To the attendants.) Arbitan? By the way I found these travel dials. Come on. Here you are! It is one of the keys of Marinus. Look around you. One of the female attendants, her hair unkempt and dressed in the plainest of robes stands by a table of scientific equipment. She has escaped into the city. She is holding four disks, one of which she places carefully on the forehead of the DOCTOR. Suddenly the eyes of the carved bearded face at the end of the room light up and the room is filled with a throbbing noise. Take them to their... laboratory. Who do we have to thank for all this?
Plan: A: TARDIS; Q: What is the name of the Doctor's time machine? A: the planet Marinus; Q: Where does the TARDIS land? A: glass; Q: What is the island made of? A: acid; Q: What is the sea made of? A: the elderly Arbitan; Q: Who forces the travelers to retrieve the keys? A: Arbitan; Q: Who is the keeper of the Conscience of Marinus? A: Voord; Q: What is the name of the race of warriors that Yartek leads? A: its originally benevolent mind-influencing power; Q: What is the original purpose of the Conscience of Marinus? Summary: 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.