When a small clipper runs aground on the crags of Fang Rock, the lighthouse offers shelter to its desperate passengers. But the Doctor soon discovers clues that suggest that no one is safe on the tiny island.
Whilst a private drama unfolds between the survivors of the wrecked clipper, another death occurs. The Doctor suspects a ruthless alien lurks in the thick unnatural fog around the island, and secures the lighthouse. But has he really locked the horror out, or is it somewhere inside with them…?
This gripping story kicked off Tom Baker’s fourth season as the Doctor.