Who Watcheth - Helene Tursten

A woman is found dead in a cemetery, strangled and covered in plastic. Just a few days before her death, the victim had received a flower, an unintelligible note, and a photograph of herself. Detective Inspector Irene Huss and her colleagues on the Goteborg police force have neither clue nor motive to track in the case, and when similar murders follow, their search for the killer becomes increasingly desperate.