Matt and his father have spent the spring building a cabin in the wilderness of Maine where they will be among the first settlers on lands occupied by the native Americans. Now that the cabin is habitable Matt's father is ready to leave to collect the rest of the family and Matt is going to stay and look after the cabin. This is a big responsibility for a thirteen year old boy and Matt is initially apprehensive but after a good night's sleep he begins to enjoy the solitude. He had been concerned that time might drag by but finds that there are barely enough hours in the day for all of the tasks he has to accomplish in order to keep the cabin running. He is a little uneasy feeling that someone might be watching him but that aside aquits himself very well.
When he sees a renegade hunter coming towards the cabin Matt thinks that this is the person who has been watching him. The man introduces himself as a hungry traveler named Ben; conscious that his father would expect him to offer hospitality he invites Ben to eat dinner with him. Ben eats heartily and tells some fanciful stories that always cast him in the role of hero, but Matt remains uneasy about him. Ben falls asleep after dinner and Matt feels cross with himself that he did not take his rifle to bed with him in case he needs to protect himself but almost immediately feels guilty for being suspicious.
In the morning Ben has left before Matt rises; he has also stolen Matt's rifle confirming Matt's initial feeling that he should have taken it to bed with him. His hinting days are now over and he is reliant on his fishing skills for food. He finds that eating fish every day is starting to frustrate him and he longs for the taste of something different. He decides to climb the tree near the cabin that has a nest of bees living in it so that he can harvest the honey. The bees become an angry swarm and sting Matt badly; he leaps from the tree and takes refuge in the creek to escape them but is on a rather bad way. He wonders if he is hallucinating when he sees an old Native American man bending towards him. He is strangely in afraid and lets the man tend to him. The next thing Matt knows, he is waking up in his own bed in the cabin with his foot bound up. The man has returned, this time with a boy around Matt's age. They have fashioned a crutch for him to enable him to move around. The man introduces the boy as his grandson, Attean. Matt wants to repay their kindness and their gifts of food but all he has to give is a favorite book, Robinson Crusoe . This gives the old man the idea that Matt should teach Attean to read the white man's signs (writing).
The lessons do not go well; although Attean is smart and easily picks up the alphabet and some words and sentences, he is contemptuous of white men and has no interest in learning his language. He does, however, enjoy hearing the story of Robinson Crusoe which Matt reads chapter by chapter each day. After the lesson the boys go hunting or fishing together. It soon becomes apparent that although Attean's grandfather saw Matt as the teacher and Attean as the pupil, it is really the other way around. Attean shows him how to make snares so that he can hunt without his rifle; he shows him how to light fires without relying on his flint, and how to spear fish. As they track through the forest Attean shows him the small marks along the route that the Indians make so that they can find their way. He also shows Matt the mark of the beaver carved into a tree which showed that the lands belonged to his tribe.
As they hunt and track one day, they come across a roly-poly, adorable bear cub. The cub is followed by a large, angry mother bear on the attack. Matt knew instinctively not to run away but wanted to enable both of the boys to escape; he threw the rabbit they had killed earlier at the bear, temporarily confusing her. As she flaps at the rabbit Attean shoots an arrow at the bear and kills her. After she falls to the ground Attean kneels by her side and whispers an apology to her for having to kill her. He then goes back to his tribe to tell the women that they need to prepare the bear for food as the Native Americans do not hunt for sport or pleasure; whatever they kill they use for food and clothing.
Attean tells Matt that he is invited to join the tribe for dinner and celebration that night to thank him for saving Attean with his quick thinking. Matt is fascinated by their camp and by the dancing that follows dinner. He feasts on bear meat and after rich food and hours of dancing he is far too tired to go home so he is given a wigwam to sleep in. He feels like one of the tribe but is saddened to hear that he was included only because Attean's grandfather wanted him there; Attean's grandmother will not allow a white person in her home. Matt realizes that this is why he was given a wigwam to himself. Attean's mother was killed by white men who scalped her and took her scalp as a trophy, mimicking what some of the Indians had done to the white men they had captured. Attean's father had left with a group searching for the killers but never returned. Matt could understand why Attean's grandmother felt the way that she did.
As Matt is going through the forest one day he hears a pained whining. He searches for what he thinks will be a trapped animal but is horrified to find that Attean's dog is trapped in a metal trap. The dog has never liked Matt and will not let him come close so Matt decides to find Attean. He runs to the tribe looking for him but only finds his grandmother who does not understand English. Attean's sister translates and then volunteers to go and get the dog with Matt. As they are freeing the pup Attean, who has been out hunting with the men all day, catches up with them as they have just freed the dog who is overjoyed to see Attean. This makes Matt suddenly homesick as he remembers his farher's dog greeting him at home. Matt is invited back to the tribe as Attean's grandmother cannot believe a white boy would go to all that trouble for an Indian dog and has revised her opinion of Matt.
Ad Fall comes, Matt realizes that his family should have arrived by now. He does not know what could have happened to them. Attean tells him that he is going into the wilderness to find his Manitou, or spirit guide. Once his Manitou appears to him he will be considered a man. When he returns from his journey he looks different; his hair is shaved into a Mohawk like the men of the tribe and he is readying himself to go on the big hunt with them. Later he confides in Matt that the entire tribe is going west because they have heard there are more white settlers coming to Maine and they do not want their ways and traditions to be changed. Attean's grandfather asks Matt to travel with them; after all, he is Attean's white brother. Matt is very tempted to leave with them but decides to wait it out at the cabin in case his family do come eventually. He is very sad to see Attean leave. Attean leaves his dog with Matt; knowing that Matt saved his life, the dog is now devoted to Matt as well.
Matt and his dog experience the onset of winter together. Matt's clothes are now thin and threadbare so he cuts up the thick wool blanket from his father's bed and fashions himself a pair of pants our of it. They are much warmer and help keep him warm enough to work in preparing the cabin in case of his family's arrival.
As Christmas approaches Matt sees a man coming towards the cabin. His dog barks loudly at the stranger but as the figure comes closer Matt realizes that it is his father. His family has finally arrived. His father explains that they had been struck by typhoid and were unable to travel until they recovered. Matt's mother does not see her little boy in Matt anymore, observing that he has grown into a man, and that he looks more like an Indian than a settler. His father observes all the signs of the Native Americans influence on Matt, like the bow and arrow hanging where the rifle had previously been. He says nothing knowing that the conversation can wait until a later time. Matt discovers that the new baby has died as he was not strong, but the family he remembers is complete, and starting their life anew together in the cabin Matt has prepared for them.