Despite his attempts to disguise himself as a tourist, the entire village community soon knows that Doren was sent by Interpol, which doesn't make his job any easier.
Doren continues his investigations, several more or less bizarre inhabitants are suspicious: for example the innkeeper who tried to force himself on Maria the night before the last murder, or the obscure village doctor who after every post-mortem examination despite clear bite wounds at the young women's throats, stereotypically insists on his heart failure diagnosis.
Even the deaf, dumb Thomas is quite nocturnal in an unseemly way, and an old fortune teller babbles about alleged vampires who are supposed to be roaming the area.
The village community is also very afraid of the mysterious Professor von Adelsberg, who is said to be working on a scientific study on the subject of "blood" at his high castle.
It doesn't take Frank Doren long to find out that the cultivated yet uncanny nobleman is behind the mysterious events.