Father and son seem to have opposite opinions in everything, musical tastes as well as politics and the war in Vietnam. Tired of arguing with his father Henry, son Gabriel leaves home. The film opens nearly two decades later, when Henry and his wife Helen gets a phone call from the hospital informing them that their son had been found wandering the streets of New York City. Gabriel has a brain tumor that has caused extensive brain damage, and needs immediate surgery. After his operation, it is discovered that the tumor damaged the part of Gabriel’s brain that creates new memories. For Gabriel, past, present and future are indistinguishable, and he still lives in the era of Vietnam and psychedelic music. Determined not to let their son slip away from them again, Henry and wife Helen vow to connect with Gabriel, who is barely able to communicate effectively. Unhappy with Gabriel’s progress, Henry researches brain injuries, which leads him to Dr. Diane Daly. She is a music therapist who has made progress with victims of brain tumors using music.
As Diane works more with Gabriel, she realizes that he seems to respond actively to the music of the psychedelic era – the Beatles, Bob Dylan and particularly the Grateful Dead. This music has a remarkable effect on Gabriel. Through this music, he is able to have conversations and express himself, all the while unaware that the era of his music has long gone. Henry can’t stand rock and roll – but he is determined to forge some memories and a new relationship with his son. As he learns the songs that animate his son’s soul, he indeed begins to form a most unusual but emotionally vibrant bond with the child he thought he had lost.