Mastro turned to Sherlock Holmes for help about a terrible crime: a monk was found dead in a monastery with wounds shown to be committed by vampires. He believes that the vampire Darth came back to avenge him because he ordered the killing of Darth's "children", bats, for some reason many years ago. Is it true that vampires come back for revenge? For Mastro, his answer is yes. But for Holmes, even though Watson believed that vampires were nesting there, he was still convinced that it was human. But he is also in a logical dilemma: it can be thought of as human, of course, but how can these strange phenomena be explained without the help of myths?