In the midst of a catastrophic August rainstorm, a grisly discovery shatters the serenity of a summer evening in northern Wisconsin. Moving quickly to prevent a panic among tourists, Loon Lake Police Chief Lewellyn Ferris enlists the forensic and interrogation skills of her close friend and fellow fly fisherman, the retired dentist "Doc" Osborne. Within hours of launching their investigation, they find themselves faced with a national media circus as Loon Lake becomes the focus of a murderous scenario that links the murder to the race for the U.S. Senate by a woman who is heir to a Northwoods fortune and other, less savory, family traditions.

In the meantime, Doc Osborne's eldest daughter, Mallory, enters into a relationship that may put her life at risk—unless her father and Chief Ferris can find the killer stalking the residents of Loon Lake.