Tom Baker
Horror Of Fang Rock

The TARDIS materialises on the island of Fang Rock off the coast of England at the turn of the twentieth century. The Doctor and Leela take shelter in a lighthouse where the keepers are just getting used to the newly installed electricity.

One of the keepers, Vince, sees a bright object fall from the sky. Later another keeper, Ben, disappears. His body is discovered behind a piece of machinery - electrocuted.

As the fog descends a small ship runs aground, and the crew seek shelter inside the lighthouse. More people die before the Doctor realises that what Vince saw was a Rutan scout, and that the Rutan has changed its form to that of Rueben.

The crew of the shipwreck had in their possession a diamond which the Doctor used in conjunction with the electric lamp to create a laser to destroy the Rutan craft, after first mortaring the Rutan itself.