 In the plot, the Voord, including their leader Yartek, have developed resistance to the Conscience of Marinus, which eliminates fear and aggression from the inhabitants of Marinus, and want to use the device for their own evil purposes.They are defeated when the Doctor's companion Ian Chesterton tricks them into destroying the machine.The Voord are killed in the resulting explosion, although it is left ambiguous as to whether Yartek escapes the explosion.