Every Christmas, Santa Claus and his dedicated team of highly skilled elves work tirelessly to create and deliver gifts to children all around the world in a single night. However, when one child out of the 600 million expecting a present is accidentally overlooked, the error is considered acceptable to everyone—except for Arthur. Arthur Claus, Santa’s well-meaning but somewhat unconventional son, refuses to let the mistake go unnoticed. Determined to correct the oversight, he embarks on an unauthorized mission to deliver the forgotten gift, racing against time to ensure that the last present reaches its rightful recipient before dawn breaks on Christmas morning.