In Canada during the spring of 1968, the cob (the name for an adult male swan) and the pen (the name for an adult female swan), both trumpeter swans, build their summer nest on a small island in a pond. The swans are worried when Sam Beaver, an 11-year-old boy on a camping trip with his father, begins coming to the lake every day to watch them; the cob believes that human boys are dangerous. One day while the pen steps away from her eggs to stretch her legs, a fox slips up behind her. Sam chases the fox away, saving both the female and her eggs. After this incident, the swans begin to trust him. After the hatching of their cygnets, the cob proudly leads his brood to Sam to introduce them. The cygnets each chirp at Sam in greeting, except for the youngest who is named Louis and is unable to chirp but pulls Sam's shoelace instead. The adult swans gradually realize that Louis is mute.