The standard third episode lull hits this story hard, as the action comes to a complete standstill at times in this episode to explain the various aspects of the plot. The Doctor, Romana, and the Mentiads take what seems to be half of the episode to dissect what the Mentiads are, how they are gaining power, and just why they have such remarkable psychic powers. No effort is made, however, to explain the Mentiads' jaundiced skin and sunken eyes. Apparently psychic dominance goes hand in hand with liver failure on Zanak.
There's another such exposition scene later when the Captain is explaining how he ransacks entire planets, and Tom Baker turns the scene into much more than a dull presentation of the plot, letting his anger at the Captain's plan boil over into a fit of rage. What makes it all the more special is when Baker stumbles slightly on a line, but keeps going, knowing, along with director Pennant Roberts, that such brilliant hell fire can't be duplicated too often.
The vast amount of exposition scenes in this episode (there's another giant one between The Doctor and Kimus where they talk about Queen Xanxia's perpetual withered state) is somewhat akin to Hitchhiker's Guide, Adams's other project that he was writing at the time, in that the story had to stop for a few minutes while Slartibartfast explained the history of Deep Thought to Arthur Dent. Adams said that the Deep Thought scene was difficult to write without killing the momentum of the story, and one wagers that he had similar reservations about Episode Three of The Pirate Planet, too.