Riddles in the night

A detective story set in the fantasy world of Naagha. The main character, Peter Fågel, investigates a series of mysterious events at the castle Mullvadd. It all starts with the disapearing of a young girl that is to be marrying the lord of the castle, soon there after the lords son is murdered and a book with some link to the events is stolen from Peter himself.
This is a part in the series of books about Naagha.