Dave, a young photon, who is forced out of the Sun on a journey of discovery. He must get to the Cassini Space Craft and save it from the forces of the Void, only Dave does not know exactly what he must do or even where the Cassini Space craft is or what it is. The forces of the Void must destroy Cassini before it sends its great discoveries back to Earth and Dave is the only thing that stands between them and victory.