(He laughs.) (IAN puts the stick into the submarine and uses the handle to grasp and pull out a wetsuit - similar to the one worn by the creature now following SUSAN.) A sea of acid! ARBITAN: At the time it was called the Conscience of Marinus. ARBITAN: To think of asking you to travel in such an absurd way! Marinus, that is the name of our planet. PYRAMID
(The rest of the TARDIS crew have reached a different side of the pyramid. The machine decided for them.
Plan: A: The TARDIS; Q: What ship arrives on the planet Marinus? A: the planet Marinus; Q: Where does the TARDIS arrive on an island of glass surrounded by a sea of acid? A: The travellers; Q: Who is forced by the elderly Arbitan to retrieve four of the five operating keys to a machine called the Conscience of Marinus? A: the keeper; Q: What is Arbitan's role in the Conscience of Marinus? A: their own sinister purposes; Q: What do the evil Yartek and his Voord warriors plan to use the Conscience of Marinus for? 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.