17-year-old Katie Price has been sheltered since childhood with a rare disease that makes even the smallest amount of sunlight deadly. During the day she is housebound, but after nightfall, Katie can venture out to the local train station and play her guitar for travelers. One night, her dreams come true when she's noticed by Charlie, whom she has secretly admired for years, and decides to hide her condition from him as the two embark on a uniquely powerful romance over one nearly perfect summer.