Almost 20 years after their teenage son Gabriel (Lou Taylor Pucci) ran away from home, Henry (J.K. Simmons) and Helen Sawyer (Cara Seymour) learn that he has turned up in a hospital. Although benign, a brain tumor has damaged his memory, rendering past and present indistinguishable. Sensing that Gabriel responds to music, Henry seeks out a music therapist (Julia Ormand), who discovers that when Gabriel listens to the rock music he loved-The Grateful Dead, Bob Dylan, Buffalo Springfield-he reengages with the world.

By deftly incorporating flashbacks, the film chronicles the souring relationship between father and son-particularly Henry's growing distaste for the music he feels is poisoning his son's mind. The striking irony is that Henry's only means to reconcile with his son is by embracing the very music that divided them in the first place.