Parts: 4
Writer: Terrance Dicks
Airdates: 3 September 1977 - 24 September 1977
Production Code: 4V

Doctor: fourth
Companion: Leela

Creature Feature: Rutans

Story: En route to Brighton at the turn of the century, the TARDIS gets "lost in the fog" and misses its destination by a few miles. Instead, the Doctor and Leela arrive on the fog-shrouded isle of Fang Rock. The only inhabitants are the three keepers of a lighthouse that has been newly converted to electricity.

But electricity seems to have turned against them, as one of the men, Vince, finds their technician dead from a massive electrical shock. Naturally, Reuben, the eldest of their group, is suspicious that the Doctor and Leela played a part in the technician's death. But the Doctor is not so sure that the generators are to blame. Leela has been sensing danger, and an unnaturally cold fog has blown in off the ocean...from the very spot where Vince saw a bright red light fall from the sky.

The lighthouse begins to experience electrical failures, and during one of these, a swiftly-travelling yacht runs aground on the rocks. Four travellers are rescued from its ruins to take shelter with the TARDIS crew and the two remaining keepers. Then, one by one, the trapped group are killed off by a mysterious and unseen presence lurking outside, so the Doctor has the lighthouse sealed. Rumors of the Beast of Fang Rock begin to circulate - last seen eighty years ago, in the 1820s, it was said to have killed two lighthouse keepers. Whether or not the legend is true, the Doctor begins to worry that instead of keeping the creature out, he has sealed it inside the lighthouse with them...