Montalbano is still moving through the five stages of grief over his advancing years (now well into his 50s) - arriving somewhere between bargaining and depression. He is a much more subdued character than previously, not as irascible and demanding, nor as unpredictable. He still harbors the hope that he can be his younger self, but his doubts interfere.
In this installment he investigates the murder of a victim who had been mutilated after death to disguise his identity and left to drift at sea. In the course of the investigation Montalbano works with a young women naval lieutenant and falls head over heels for her. Needless to say, the relationship is difficult at best.
Through a combination of luck and insight, Montalbano gets to the bottom of the mystery surrounding the murder, uncovering an international conspiracy and running headlong into another parallel investigation. The novel ends with a movie-worthy action sequence, and with … well, that would be telling.