Detecting a mysterious sub-space signal in the Time Vortex, the Doctor and Ace land on the planet Blinni-Gaar. They soon discover that the native population are little more than zombies, addicted to the programmes of the dangerously powerful Channel 400. As the Doctor investigates, he finds that the television company has a sinister agenda that has nothing to do with entertainment. As the Doctor is drawn deeper and deeper into a web of intrigue and deceit he discovers that he has an unexpected ally — of the most dangerous kind.