The novel follows Joe Coutts, a thirteen-year-old living on an Ojibwe reservation in North Dakota. Joe, who is also the story's narrator, lives with his father, Bazil, and his mother, Geraldine. Bazil is a tribal judge, and Joe is initially respectful of his father's "noble profession." As the story begins, we learn that Geraldine has suspiciously not returned home after running errands. After Joe and Bazil leave home to look for her, they discover that Geraldine has been brutally raped and attacked by an unknown assailant.
Seeking justice, Joe and Bazil repeatedly run into roadblocks with their case. Frustrated by judicial incompetence, Joe and Bazil resolve to piece the case together themselves. Joe enlists the help of his three teenage friends–Cappy, Angus, and Zack. Together, the boys go to the scene of the crime and attempt to discover evidence that will lead them to identify the attacker. Meanwhile, Bazil attempts to cooperate with authorities while launching his own investigation.
The boys initially think that the new priest in town, Father Travis, could be a suspect in the crime. However, after spying on him, they realize that he has a legitimate alibi. Joe and Bazil work together to initiate a conversation with Linda Lark, an anomaly in the local Native community. Linda was born into a white family, adopted by Ojibwe parents, and raised on a reservation. The Lark family gave Linda up for adoption due to the physical deformities she had at birth. Throughout their conversations with Linda, Bazil and Joe realize that Linda's twin brother, Linden, is a prime suspect.
One day, while searching for potential evidence at the lake, Joe finds a doll head floating in the water. Upon further investigation, he realizes that there is a large sum of money stuffed into the head. He tells Sonja, a former stripper who he has a crush on, about the discovery, and she goes around town depositing the cash into various banks to save for Joe's college. As time goes on, Joe realizes that Sonja is using the money herself. Joe is not the only one who finds Sonja's behavior suspicious—Whitey, Sonja's husband, is suspicious of his partner's infidelity. Sonja soon leaves town, taking most of the money with her in hopes of starting a new life.
Joe spends some time with his grandfather, Mooshum. Mooshum tells Joe about the history of the round house and the Wiindigos—evil, possessed spirits. Back at the lake, the authorities have found a sunken car that belongs to Mayla, a young woman attacked by the same person that attacked Geraldine. Joe realizes that the large sum of cash recovered at the lake is connected to Mayla's disappearance and his own mother's attack.
Meanwhile, Linden keeps popping up around town. He appears at the gas station where Joe works, and he is also at the grocery store in town. Bazil grows upset when he sees Linden in the grocery store aisle, and he physically attacks him due to the pain he has caused Geraldine. Bazil has a heart attack after he lunges at Linden, and Joe realizes that his entire family is suffering as a result of Linden's actions. Joe devises a plan to kill Linden so that his family may find peace.
Joe recruits Cappy, an accomplished hunter, to help train him in using a gun. After some time anxiously planning and practicing to kill Linden, Joe eventually carries out his plan. He shoots Linden in the stomach, leaving him injured but still alive. Cappy shoots the final shot, killing Linden on the golf course. They hide the murder weapon on Linda Lark's property. Many people are suspicious of Joe's involvement in Linden's murder, and Joe is visibly anxious following his crime. However, Whitey helps Joe and Cappy develop a strong alibi, and the two are undiscovered by the authorities. Linda Lark even realizes that Joe killed Linden, but she chooses to keep this information to herself. She later tells Joe the entire story that provides Linden with a motive for his violent crime.
Cappy, Joe, Angus, and Zack visit Montana in order to help Cappy court Zelia, a missionary girl he has fallen in love with. While en route, Cappy crashes the car. While Joe, Angus, and Zack sustain minor injuries, Cappy dies from the accident. Bazil and Geraldine come to collect Joe from his journey, and they drive him home.
