As the story opens, Brian has set out to spend time in the wilderness. He plans to stay mostly by himself but has promised to work on some school work that he'll be tested on when he returns later to the city. Brian is sixteen years old and could have simply dropped out of school at this point but has discovered an incredible thirst for learning. He no longer is satisfied with simply memorizing facts in order to pass a test but now really wants to learn.

Brian's life and thoughts have been shaped by an event two years earlier when he was only fourteen. He'd been the only passenger on a small plane when the pilot died and the plane crashed in the Canadian wilderness. Brian recalls how incredibly inept he was at first as he tried to survive with no tools but a hatchet. He remembers the first time he'd managed to catch a fish and how he'd gradually become self-sufficient in the woods with no other people around. Then he'd been rescued and returned to the city and his parents. But Brian discovered he didn't fit in. The noises upset him and he hated the constant activity. He'd convinced his parents and the school officials to let him have time in the wilderness alone. He wasn't angry at anyone but had decided this is the life he now wants to lead.

Brian is traveling by canoe at a leisurely pace. His ultimate destination is the home of his Cree friends, David and Anna Smallhorn, who are camped on an island at the upper end of a lake shaped like an arrow. One evening David eats his supper on the banks of the lake and then pushes his canoe back into the water where the breeze will help keep the mosquitoes at bay. He's suddenly aware of a noise and discovers it's a dog. David is wary wondering where the dog came from, but soon discovers the dog is seriously injured. He considers possible causes of the wound but none of them make sense. David sews up the dog's wound and she immediately attaches herself to him. He's glad of the company and sets out for the next leg of his journey with the dog in the front of the canoe.

After traveling only a short distance more, David stops and kills a deer, feeding the dog all she can eat in an effort to help her rebuild her strength. He continues to consider the possible causes of her wounds and is suddenly struck with an overwhelming fear for his Cree friends. He rushes the rest of the journey and arrives at their camp to discover the bodies of Anne and David, mauled and partly devoured by a bear. He then finds several other dogs, all killed by the bear. Brian is fearful for the three children of David and Anne and takes time to scout for tracks and signs of what happened. He discovers the oldest daughter, Susan, in a canoe on the opposite shore of the lake, and brings her back. She's exhausted but unhurt and reveals that her younger siblings were visiting family in the city.

Brian buries the bodies and Susan uses a radio to call for help. Officials arrive and take Susan to her relatives but Brian declines the offer of a ride back to civilization. He sets out to find the bear with the help of the dog and soon discovers that the bear is actually tracking Brian. When they meet, Brian is nearly beaten by the bear until the dog jumps into the fight. Brian is able to kill the bear with arrows.