When Moon was a young princess of the Light Kingdom of the planet of Avinar, she was injured by an attacking Darksider. With her powers that most of Avinar's nobility posses being absent for her, she doesn't have the healing ability to survive. That is, until her sister Halley sacrifices some of her immense power to save her, and giving her powers in the process. Ten years later, the Darksiders attack, forcing the King and Queen to send their daughter to a planet called Earth to find safety and help. After a crash landing in a strange place known as Jump City and running from the Trackers her enemies sent for her, Moon thinks she has failed. That is, until the three teenage vigilantes arrive on the scene.