A young, musically gifted boy, Evan Taylor, finds himself shuffled between various foster homes in New York. He possesses an exceptional talent for hearing music in the world around him, a trait he believes will eventually reunite him with his birth parents, whom he has never met but feels certain are searching for him. Despite the challenges of his environment, Evan's conviction that his parents want him propels him to take a leap of faith. Under the pseudonym "August Rush," he sets out on a journey to find them, guided by the symphonies he hears in everyday sounds. His unusual auditory gift acts as his compass, leading him through the complexities of the musical world.

On the other side, the story intricately weaves in the narrative of Evan's parents, a young concert cellist and a rock musician, who had a serendipitous one-night encounter, resulting in Evan's birth. Unaware of each other's identities and the existence of their son, they are both haunted by the memories of that night and the music they created together. Their separation, compounded with their lost son's quest, forms a parallel narrative of love, fate, and the undeniable pull of music. As Evan navigates his way through the music scene, his parents grapple with their past decisions and the mystical, musical thread that seems to draw them together.