On the distant planet Lumimaire, the ultimate energy source that powers the great city Luminicity - the Lightstar Crystal - has been split in half. Two fractions now own one half of the Crystal and battle to obtain the other half which will give them control over the planet. The heroic Legion of Light, consisting of Justin Lightstar a.k.a. Prince Lightstar, Joshua Lightstar a.k.a. Grimskull, Jennifer Lightstar a.k.a. Talyn, has been endowed with great powers through their half of the Crystal. They team together with their uncle Ursak to battle the evil Baron Dark. The Baron gained control of the other half of the Crystal, which transformed him into a living skeleton, also granting him the ability to transform others of evil heart into living skeletons for his legion. It is the battle between the light and dark sides.