5. Horror Of Fang Rock
The localised condition of planetary atmospheric condensation caused a malfunction in the visual orientation circuits. Or to put it another way, we got lost in the fog.
A story with atmosphere in droves, the Doctor and Leela find themselves trapped in a Victorian lighthouse, surrounded by misty waters with an alien force lurking within, killing off the inhabitants one by one. It is a tense story and a brutal one, too. The death toll continues to rise as the episodes progress. The claustrophobic nightmare proves that you don't need a big budget or even an elaborate story to do a really creeper sci-fi horror. The inhabitants and visitors to the lighthouse finding themselves being picked off one by one is rather scary. The Rutan itself - a green glowing blob - isn't the best alien design but it serves its purpose in being something entirely different to what you might first expect. Add in the greater mystery - that the Rutan is a scout for an invading alien force - and the stakes become much higher. One for which the Fourth Doctor is up to the challenge.