Horror of Fang Rock On a remote island, the occupants of a lighthouse and the survivors of a shipwreck fall victim, one by one, to a ruthless alien that has the ability to transform its appearance. The Invisible Enemy When the Doctor is infected by a sentient virus, clones of himself and Leela must journey into his own brain to confront the enemy. Image of the Fendahl Attempts to unlock the secrets of a skull that predates the birth of man release the Fendahl, an ancient evil that could destroy the world. The Sun Maker The human population of Pluto is subjugated by extortionate taxation, imposed upon them by the ruling Company, so the Doctor and Leela lend their hands to the rebellion.