It’s the summer of 1768, and 12-year-old Matt has been left in charge of his family’s new homestead in rural Maine. Matt and his father arrived several months ago to clear the land and build a cabin, and now Matt’s father has returned to Massachusetts to fetch Matt’s mother, Matt’s sister Sarah, and the new baby, who will be born before the family is reunited. Matt’s father left him with his good rifle and passed along his precious watch before leaving. He’ll be back in six or seven weeks. Matt will turn 13 while his father is gone.
After a few days, Matt is thrilled with his solitary life. He relishes his freedom to do his chores without annoying commentary, and there’s more than enough work to keep him busy. He fears Native Americans are watching him from the woods, but Matt can’t be sure. A few weeks in, a white man named Ben appears in the clearing. Ben invites himself to stay for supper and ends up spending the night in the cabin. He tells Matt all about his youth spent with local Native tribes and fighting in the various wars between the Native Americans and colonial powers. When Matt wakes up in the morning, he realizes that Ben took the rifle with him. Matt now must rely on fish for meat.
After Ben leaves, Matt’s life finds a rhythm again—until he forgets to bar the cabin door, and a bear ransacks the cabin. It eats all of Matt’s dry goods and molasses. Soon after, Matt decides to try to take honey from a wild beehive. The bees chase him into a pond after stinging him incessantly. A Native man rescues Matt from the pond, removes the bees’ stingers, and tends to Matt for a few days while he recovers. When Matt is well again, the man introduces himself as Saknis and brings his grandson, Attean, to visit. Attean is a little older than Matt, and he clearly detests Matt. To thank Saknis for his kindness, Matt offers him his copy of Robinson Crusoe. Saknis can’t read, but he strikes a deal with Matt: Attean will bring Matt meat, and Matt must teach Attean to read. This way, Attean will be able to read treaties and can refuse to sign away his tribe’s hunting grounds.
The reading lessons go poorly. Matt finally tries to capture Attean’s interest by reading Robinson Crusoe to him, which works—until he reads the passage where Crusoe rescues and then enslaves the Native man Friday. Attean is so offended that he storms out. Matt has to confront that perhaps his favorite novel isn’t presenting a realistic view of Native people, since Matt knows now that Native people are intelligent. He begins censoring the book, reading only the exciting parts to Attean and omitting anything boring or offensive.
Attean begins taking Matt into the woods after their reading lessons, where they fish and hunt. Attean shows Matt how to make fishhooks out of twigs and snares out of tree roots. He also shows Matt a beaver dam and how to recognize trail markers and territory markers—his beaver clan can only hunt where trees are marked with beavers, while they must stay out of territory where the turtle clan has marked trees with turtles. This is difficult for Matt to grasp, especially when the boys find a fox struggling in a turtle hunter’s iron trap one day. Attean insists they can’t save or take the fox for themselves. He also explains that more tribes these days are using European hunting methods, like iron traps, to trap animals for pelts. The animals that were once plentiful in the forest are now almost gone because of this. Attean also helps Matt make a proper bow and arrows.
One day, when Matt and Attean are in the woods, they come across a bear cub and must kill the mother bear before it attacks them. Attean is able to shoot it with an arrow because Matt momentarily distracts the bear by throwing a dead rabbit at it. To thank him for his help, Saknis invites Matt to join the tribe for a feast. Matt is nervous at first, but he happily dances, eats, and stays the night with the tribe. As Attean leads Matt home the next morning, Attean makes it clear that Matt won’t be welcome back to the village: since bounty hunters murdered Attean’s mother just to take her scalp, Attean’s grandmother hates all white people. Attean’s father never returned when he left to avenge his wife’s death, which is why Attean lives with his grandparents.
However, when Matt finds Attean’s beloved dog stuck in a turtle iron trap one day, he knows he must go back to the village so he can get help and free the dog (the dog doesn’t trust white people and has never liked Matt). Attean isn’t around, but Attean’s grandmother allows Attean’s little sister, Marie, to help Matt. Together, he and Marie save the dog. This incident gives Attean’s grandmother newfound respect for Matt, and Matt accepts an invitation to spend a day in the village. He plays and roughhouses with Attean and Attean’s friends. To his surprise, it feels like being back at home—and Attean’s dog finally acts like it likes Matt.
One day, Attean visits and says he’s going away for a while. It’s time for him to undergo his tribe’s ritual to become a man, wherein a boy must live alone in the woods without eating until their “manitou,” or spirit, appears. When he finds his manitou, he’ll get a rifle so he can hunt moose this winter. Matt hopes Attean finds his manitou.
A few weeks later, in the late fall, Attean and Saknis enter the clearing—and as Attean’s hair is now cut in an adult style and he holds a rifle, Matt realizes he found his manitou. Saknis explains that he’s come because Matt’s father was supposed to return weeks ago, so he’d like to invite Matt to join the tribe when they go north soon. Matt can be his grandson and Attean’s brother. On one hand, Matt wants to go, but he insists he must stay. Saknis shakes Matt’s hand and Attean follows him away.
Attean returns a few days later with gifts from his grandparents: snowshoes and maple sugar. He also has a gift for Matt himself: he’s going to leave his dog for Matt. Attean says he respects Matt’s decision to stay and wait for his father, and he’d make the same choice if his father was still alive. As a parting gift and as a token of their friendship, Matt gives Attean his father’s watch. In parting, Attean calls Matt his brother.
Matt and the dog spend the next weeks preparing for winter. They chop wood, hunt as much as they can, fish, and gather various roots and berries to dry. Using what he learned from Attean, Matt makes himself fur mittens and a hat to keep warm. When it snows heavily for the first time, Matt enjoys using the snowshoes.
A few days later, after another heavy snowfall, the dog starts barking: Matt’s father, mother, and Sarah are walking up the frozen river with a sled. They’re so late because the whole family had typhus, and they were late leaving Massachusetts. They are very surprised to learn that Matt befriended Native Americans, and Matt learns that his baby sibling died a few days after birth. When Matt’s father tells Matt he did a man’s job at the cabin, Matt feels like an adult—and he believes that his feelings of pride are exactly what Attean must’ve felt when Attean found his manitou. Though Matt is a bit sad to learn that several families are planning to settle in the area—meaning he will no longer have free reign over the woods—he’s ready to move forward and continue to support his family.