The Case Book of Arne follows Arne Neuntöte, a vampire detective who can manipulate supernatural powers, and Lynn Reinweiß, the daughter of a nobleman who has always loved vampires. Their lives are meant to stay far apart, but one desperate night leads Lynn into Lügenberg, a mysterious city where non-humans live openly and strange rules govern everyday life. There she meets Arne, a vampire notorious in the city as "the worst," and the encounter pulls her into a bloody mystery that has been waiting to surface.
As a new murder case unfolds, Lynn and Arne are forced to work side by side, gathering clues while the boundary between humanity and the bizarre grows thinner with each revelation. In Lügenberg, supernatural beings hide in plain sight, and every answer seems to expose a deeper wound beneath the crimson moon. Surrounded by danger, suspicion, and the city's own unnatural order, the pair must uncover the truth behind the bizarre incidents haunting Lügenberg before the case consumes them both.
