Henry Roth, a marine-life veterinarian living in Hawaii, meets Lucy Whitmore, an art teacher, in a cafe one morning. They hit it off and agree to meet in the cafe the next morning. The following day, however, Lucy claims not to know Henry. The cafe owner pulls Henry aside and explains that Lucy suffers from anterograde amnesia (called 'Goldfield Syndrome' in the movie) from a car accident she was in a year earlier. Her condition has left her with no memory of anything between the day of the accident and the present, because she is incapable of converting short-term memories into long-term memories.
At the beginning of each day, she loses all memory of the past day. She innocently believes every day to be October 13, 2002. Her father and brother attempt to reenact the activities of October 13th, her father's birthday, every day, to prevent her from suffering from learning about the accident.