An overly critical father gets a unique opportunity to reconnect with his estranged son, if he can only embrace the music that once divided them in this uplifting family drama inspired by Dr. Oliver Sacks' case study "The Last Hippie." Forbidden by his conservative engineer father, Henry (J.K. Simmons), from attending a Grateful Dead concert back in 1967, Gabriel Sawyer (Lou Taylor Pucci) packs his bags and runs away from home. Twenty years later, Henry and his wife, Helen (Cara Seymour), receive word that Gabriel has been diagnosed with a benign brain tumor that requires delicate surgery to remove. Though the operation is successful, Henry and Helen soon learn that the part of their son's brain responsible for creating memories has been damaged by the long-neglected tumor, and that as a result, Gabriel will find it difficult to distinguish the past from the present. As communication grows increasingly difficult, frustrated father Henry becomes staunchly determined to make up for lost time by forming a solid father-son bond with Gabriel, and begins researching treatment for brain injuries. It isn't long before Henry's inquiries lead him to music therapist Dr. Dianne Daly (Julia Ormond), whose innovative methods have yielded impressive results in the past. When Dr. Daily exposes Gabriel to the rock & roll music that he loved as a youth, something incredible begins to happen: Gabriel finally finds the words to express himself, and he regains the ability to have meaningful conversations. As his own health begins to take a turn for the worse, Henry determines to let go of his loathing for the music that has awakened his son's consciousness, and embrace the joy of loving the child he once drove away.