Trevor McKinney, a seventh-grader in Las Vegas, receives a life-changing assignment from his social studies teacher, Eugene Simonet. The task is simple yet profound: devise and implement a plan to change the world for the better. Inspired, Trevor creates “Pay It Forward,” a concept where each recipient of a favor must pass on three significant acts of kindness to others instead of repaying the original favor. This ripple effect begins with Trevor himself.
His first act of kindness is offering shelter to a homeless man named Jerry, allowing him to stay in his family’s garage. Jerry, in turn, helps Trevor’s mother, Arlene, with car repairs, but disappoints Trevor when he falls back into drug addiction and disappears. When Arlene discovers Jerry in their home, she confronts Eugene about the project, expressing her concerns. Meanwhile, Trevor decides to focus on Eugene next, orchestrating a dinner between him and Arlene in the hope of sparking a romance. The plan initially falters, leading to an argument between Trevor and his mother over her lingering attachment to Ricky, her alcoholic ex-husband. In a moment of frustration, Arlene slaps Trevor, deepening their rift.
When Trevor runs away from home, Arlene seeks Eugene’s help to find him. This shared concern reignites their connection, and Arlene begins to pursue Eugene romantically. However, Eugene is haunted by his past. His body bears scars from severe burns, inflicted by his abusive father, a man his mother repeatedly took back despite the violence. Initially, Eugene resists Arlene’s affection out of fear and insecurity, but he eventually opens up. Their relationship blossoms, only to be derailed when Ricky returns, claiming sobriety. Against Eugene’s warnings, Arlene gives Ricky another chance, echoing the cycle of her own mother’s poor choices. Ricky soon reverts to his old ways, drinking and lashing out, forcing Arlene to confront her mistake and throw him out for good. Meanwhile, Jerry finds redemption by preventing a man from committing suicide.
The story unfolds non-linearly, beginning with an anonymous act of kindness. A stranger gifts a car to journalist Chris Chandler in Los Angeles, setting him on a path to uncover the origin of “Pay It Forward.” Through his investigation, Chris follows the chain of selflessness, tracing it back to Trevor’s school project. Along the way, Arlene reconciles with her estranged mother, Grace, who then helps a young gang member evade the police. That gang member later saves a little girl’s life, whose grateful father gifts Chris his car.
Chris finally reaches Trevor and records an interview with him, capturing the young boy’s vision and fears for his movement. Eugene, upon watching the interview, realizes that he and Arlene belong together. As they reunite, Trevor spots his classmate, Adam, being bullied. Without hesitation, he intervenes, embodying his own philosophy of selflessness. In the scuffle, one of the bullies pulls a knife, and Trevor is fatally stabbed. He succumbs to his injuries at the hospital that evening, his life ending far too soon.
News of Trevor’s movement spreads across the country, his death only amplifying its impact. Strangers, inspired by his actions, continue to “pay it forward.” In an emotional climax, Arlene and Eugene watch as thousands of people gather outside their home, candles in hand, honoring Trevor’s legacy. His idea, once a mere school project, has become a movement—a testament to the power of kindness.