From publisher blurb: Vampire Undercroft is a Fifth Edition plug-in adventure for four characters with an average party level (APL) of 8, 11, 14, or 17. This document offers details for each level and makes adjustments accordingly. In the bowels of a flying castle, a cursed vampire has made his lair. If the characters want to clear the area of evil, they must contend not only with him but the other guardians of the undercroft.