1. Trevor McKinney is given an assignment by his teacher, Mr. Simonet, to create a concept to change the world. He creates the concept of "Pay it Forward" which involves doing large favors for three strangers and encouraging them to do favors for three more people.
2. Trevor's first favor is helping a homeless man by bringing him home, feeding him, and giving him money to buy clothes. His second favor is helping his alcoholic mother recover.
3. While trying to help a friend who was being beaten, Trevor is stabbed and dies, but he inspired many with his idea of paying kindness forward.