Soggy Goths. Suspenders. Batman Labeled Poison Gas Bombs. Dogging. Lots of dogging. Yes, it's the Curse of Fenric.
This episode covers, more or less, episodes 1 and 2 of the story from 1989. Part II, next week, will cover the rest of it.
WARNING: You will not look at the Third Doctor in the same way again after this.