A murderer stalks the streets of Caliphas, a slasher who only hunts a particular type of victim: vampires. As the heroes track the cultists of the Whispering Way, they lose their quarry amid the mazelike alleys of Ustalav’s crowded capital city. But from the shadows, a dark patron rises with offers of aid and insights into the cult’s ultimate evil. All he asks in return is that the adventurers put an end to the murderer terrorizing the city’s vampires. This leads the heroes into an underworld of endless night, where they must explore the vampires’ deadly society and indulge its blasphemous traditions if they’re to discover who’s murdering the undead. What they uncover is a conspiracy of blood, and a union of evils willing to risk both life and undeath in the pursuit of ever-lasting youth.