The Master reveals to the trapped Adric that he has a further trap set for the Doctor. Tegan searches the TARDIS computer systems and finds a place named the Dwellings of Simplicity on Castrovalva which will be a suitable place for the Doctor to recover from his regeneration, but when they arrive the Doctor vanishes!
The TARDIS enters the universe of E-Space and lands on the planet Alzarius where Mistfall is occurring and creatures are stirring in the swamp.
Romana has been infected by the bite of a marsh spider and the Doctor discovers that the ruling Deciders have been perpetuating a lie to their own people.
The Doctor and K-9 are stranded when the TARDIS is stolen by the Marshmen. Romana encounters the Outlers who are regretting their decision not to return to the Starliner.
Nyssa and Tegan follow the trail of blood away from the Cabinet, trying to find the Doctor while avoiding the feathered warriors in the forest. They eventually spot the Doctor some distance away, but although they call out to him he doesn't recognize his own name. The warriors take the Doctor into Castrovalva with them, but Nyssa and Tegan arrive seconds too late.
