DOCTOR WHO IN DETAIL

The TARDIS lands on the planet of Marinus, a world where the beaches are glass and the sea is acid. The planet is controlled by the Conscience, although four of the five operating keys have been lost. Arbitan, Keeper of the Conscience, captures the TARDIS and forces the Doctor and his crew to search for the keys.

Their quest takes them to many differnt places on Marinus, including the futuristic city of Morphoton, a deserted jungle, an ice-bound wilderness, and the city of Millenius.

On their return they find Arbitan has been killed by Yartek, leader of the Voord. Yartak forces Ian to hand over the keys that have been retrieved. One of the keys that Ian hands over is a fake, and when used the Conscience of Marinus explodes, killing Yartak and the Voords and freeing the people of Marinus from control.