While performing an autopsy, coroner Paul Herzfeld (Moritz Bleibtreu) discovers a note in the skull of a corpse with a phone number which belongs to his all but estranged daughter, whom he soon discovers has gone missing. The sinister clue leads him on the trail of a deranged killer, who has planted similar clues that must be uncovered in order to save the young woman. Enlisting the reluctant help of an artist and an eager intern, Paul unravels a mystery whose threads run deep and that leads him to a solitary island cut off from the mainland by a winter storm.