The unnamed narrator returns to Quebec after years of absence to search for her missing father. She brings her boyfriend, Joe, and a married couple, Anna and David. On the way to a village near her father’s island, the narrator visits her father’s friend Paul. Paul can provide no new information on how to locate the narrator’s father. A guide named Evans takes the narrator and her companions to her father’s island, where the narrator searches for clues regarding her father’s disappearance. She becomes convinced that her father has gone mad and is still alive.
The narrator works in spurts on her freelance job illustrating a book of fairy tales, but her worries prevent her from accomplishing any real work. David proposes staying on the island for a week. The narrator agrees, though she secretly fears her crazed father’s reemergence. During their stay, David launches constant insults at Anna, couching them as jokes. Anna confesses to the narrator that David is a womanizer. She complains that David constantly demands that Anna wear makeup. The four go on a blueberry-picking expedition. They canoe to a nearby island, where Joe unexpectedly proposes to the narrator. The narrator refuses Joe, telling him how she left her last husband and child.
Back on the island, Paul arrives with an American named Malmstrom. Malmstrom claims to be from a Detroit wildlife agency. He offers to purchase the island, but the narrator refuses. She pulls Paul aside and tells him that her father is still alive. Paul seems skeptical. After the visitors leave, David offhandedly accuses Malmstrom of being a C.I.A. operative who is organizing an American invasion of Canada. The narrator looks through her father’s records and consequently believes that he is likely dead. She sees that he had been researching Indian wall paintings and that he had marked several sites on a map. She decides to visit a site.
The narrator convinces her friends to accompany her on a camping trip to see the wall paintings. On their way to the campsite, they see a decomposing blue heron that has been hanged from a tree. David insists on filming the dead heron for a movie he is making called Random Samples. The heron’s death haunts the narrator. She sees evidence of two campers entering the area beforehand, and she quickly assumes that they are Americans and to blame for the crime. Meanwhile, the four companions set up camp. Anna tells the narrator she has forgotten her makeup and David will punish her. The narrator goes fishing with David and Joe. They encounter the Americans, and the narrator notices an American flag on their boat. The narrator brings her companions to a site from her father’s map, but there are no wall paintings. Frustrated and confused, they return to camp. On the way, they again encounter the American campers. The narrator is surprised to discover that the campers are actually Canadian; what she had thought was an American flag is actually a sticker. However, the narrator claims the campers are still Americans because their slaughter of the heron is a distinctly American action.
The four return to the cabin. The narrator locates another site on her father’s map but realizes that the government has raised the water level in this part of the lake. She will have to dive to see the paintings. Outside, the narrator observes David tormenting Anna by insisting she take off her clothes for Random Samples. Anna eventually relents but then feels humiliated. The narrator asks David why he tortures Anna, and David claims he does so because Anna cheats on him. The narrator canoes to a site from her father’s map. She dives repeatedly in search of the paintings. On a particularly deep dive, she sees a disturbing object and screams and swims for the surface. Joe has followed her onto the lake and demands to know what she’s doing. She ignores Joe and realizes that what she saw was a dead child. She believes it to be her aborted baby. She changes her story from leaving her husband and child to having an affair with her art professor and being forced to abort their baby.
The narrator’s vision throws her into a psychosis. She believes that her father had found sacred Indian sites and resolves to thank the gods for granting her “the power.” Joe tries to speak to the narrator, but she remains impenetrable. He tries to rape her, but he leaves her alone once she warns him that she will get pregnant. Later, David tries to seduce the narrator, telling her that Joe and Anna are having sex. The narrator nevertheless resists David’s advances. A police boat comes to the island, and David tells the narrator that the police have found her father’s body. Deep in her madness, the narrator refuses to believe David. That night, she seduces Joe so she can get pregnant. She feels that a new child will replace her lost baby. Joe falsely believes that the narrator has forgiven him for cheating on her.
On their last day on the island, the narrator abandons her friends. She destroys David’s film and escapes in a canoe. The narrator’s companions search in vain for her, eventually leaving the island. Alone on the island, the narrator falls deeper into madness. She destroys the art from her job and nearly everything inside the cabin. She becomes an animal, running around naked, eating unwashed plants, and living in a burrow. She imagines raising her baby outdoors and never teaching it language. She also has visions of her parents. Eventually, hunger and exhaustion bring the narrator to sanity. She looks at herself in the mirror and sees just a natural woman. She resolves not to feel powerless anymore. Paul arrives at the island with Joe. The narrator realizes she loves Joe and resolves to reunite with him. She pauses in the cabin, looking out at Joe, waiting.