Brian Robeson is a thirteen-year-old son of divorced parents. As he travels on a Cessna 406 bush plane to visit his father in the oil fields in northern Canada for the summer, the pilot suffers a massive heart attack and dies. Brian tries to land the plane, but ends up crash-landing into a lake in the forest. He must learn to survive on his own with nothing but his hatchet—a gift his mother gave him shortly before his plane departed.
Throughout the summer, Brian learns how to survive in the vast wilderness with only his hatchet. He discovers how to make fire with the hatchet and eats whatever food he can find, such as rabbits, birds, turtle eggs, fish, berries, and fruit. He deals with various threats of nature, including mosquitos, a porcupine, bear, skunk, moose, wolves, and even a tornado. Over time, Brian develops his survival skills and becomes a fine woodsman. He crafts a bow, arrows, and a fishing spear to aid in his hunting. He also fashions a shelter out of the underside of a rock overhang. During his time alone, Brian struggles with memories of home and the bittersweet memory of his mother, whom Brian had caught cheating on his father prior to their divorce.
When a sudden tornado hits the area, it draws the tail of the plane toward the shore of the lake. Brian makes a raft from a few broken off tree tops to get to the plane. When Brian is cutting his way into the tail of the plane, he drops his hatchet in the lake and dives in to get it. Once inside the plane, Brian finds a survival pack that includes additional food, an emergency transmitter, and a .22 rifle. Back on shore, Brian activates the transmitter, but not knowing how to use it, he thinks it is broken and throws it aside. However, his distress call is heard by a passing airplane, and he is rescued.