Who is behind the homicides in the coastal area of Quai Natia? What is the meaning of the lapel pins left on all the victims? And will the killer outsmart the authorities and declare victory in the end?

Under a perfect cobalt sky in the idyllic town of Quai Natia, four golfing buddies stroll down the fairway of the first hole. Unsuspectingly, they make a startling discovery that will soon spook the local community. Before long, red-haired Lt. Rhombus is summoned to address the apparent crime. Little does he know that he and his team are destined to find more bodies in the ensuing weeks.

Nothing at the crime scenes suggests the cause of death, but eventually, the town's talented medical examiner uncovers how all the victims were murdered. Still, how can this information be used to identify the local menace? With the scarcity of physical evidence, Lt. Rhombus and his confreres need to decipher every clue, no matter how trivial. And the lieutenant comes to realize that his crime-solving skills will be put to the test as he oversees the hunt for the elusive Black Bird Killer.