The Lesbian Vampire Killers plot revolves around two down-on-their-luck slackers, Fletch (James Corden) and Jimmy (Mathew Horne). After Jimmy is dumped by his on-again-off-again girlfriend, Judy, and Fletch is fired from his job as a children's clown, they decide to temporarily escape their woes and go hiking to a remote and, to them, unknown village selected by throwing a dart - while drunk - at an old map.
The fellowship arrive at their destination, only to find that an ancient curse rests over the village and that every female child, at their eighteenth birthday turns into a lesbian vampire. This is the result of an old legend, where the Vampire Queen, Carmilla, descended on the village, killed its menfolk and seduced its women to her evil.