When the body of a man is discovered at the base of some cliffs in the small resort town of Hari Cove, the police initially suspect a tragic accident, a mistake that cost the man's life. However, when the victim is revealed to have been a former police officer and that the cause of death was actually carbon monoxide poisoning, they begin a murder investigation. Manabu Yukawa, the physicist known as 'Detective Galileo', is in Hari Cove to speak at a conference regarding a planned underwater development, and he decides to take on the case. Was the murder related to the small community's attempt to rejuvenate, or does it have its roots in the town's history? In a series of twists as intricate and surprising as in Higashino's brilliantly praised work, Yukawa uncovers the hidden connections behind the tragic events that led to this murder.