"Clouds" follows Zach Sobiech's final year after he learns his osteosarcoma is terminal. The central plot revolves around his decision to create music with his best friend Sammy to say goodbye. They get a BMI contract and record the song "Clouds," which becomes a viral YouTube hit, bringing unexpected fame.
A key emotional subplot is Zach's relationship with Amy. Fearing the pain his death will cause her, Zach breaks up with her. This is a fictionalized element added for dramatic effect, as the real couple never broke up. In the film, they eventually reconcile, choosing to cherish the time they have left.
The film's climax is a combined prom and concert, where Zach, in rapidly declining health, performs. He struggles to sing "Clouds" due to his failing lungs, but in a deeply moving moment, the entire audience sings the lyrics back to him, fulfilling his dream of hearing a crowd sing his words. This concert is a composite of three separate real-life events: a concert, a party, and his actual prom.
The film ends with Zach's death on May 20, 2013. His mother finds his completed college essay, which serves as a final, poignant narration on what he learned about life. The final scene shows his friends Sammy and Amy taking a picture together sometime later, noticing a cloud in the sky shaped like a 'Z'—a symbol of his lasting presence. The credits feature archival footage of the real Zach Sobiech, his friends, and family, reinforcing the story's authenticity and powerful real-world legacy.