Tod in Valantia (2010)

(from the back of the book)
Sidor Valantis, the roaring metropolis at the Valant Sea, is known for its colorful mixture of people and their extravagant lifestyle. Especially in "Sang", the days of the year in which Raia is honored and the streets are filled with revelers. The days that culminate each year in the splendid, pompous Raia festival.
This year again there is a lively atmosphere when the heroes arrive in Sidor Valantis, but plans to enjoy the raucous festival are soon forgotten, for death comes to in Valantia! A series of highly unusual deaths draws the hero in a current of dangerous intrigue, lust and revenge that drives them right through the confusing streets and canals of Rumakra. Finally the task to prevent more victims becomes more compelling as they themselves come under suspicion of being involved in the incidents and have to fear for their lives.