It's Christmastime and Caillou's family is gathering together. Even his Aunt Poppy and her cat Balthazar have come from far away to celebrate the holiday with Caillou, his sister Rosie, and their parents and grandparents. Before they know it, Christmas Eve has arrived, and Caillou-who is too excited to sleep-suddenly hears a strange noise. Could it be Santa? Capturing the precious memories and emotions of the holiday season, toddlers learn about the deeper meaning of Christmas.