The show takes place in the fictional planet of Luminaire, and mostly in the metropolis of Luminicity. The villainous Baron Dark attempted to steal the Lightstar Crystal which powers the city, but accidentally shattered it and escaped with half of it in his hands. It transformed him into a living skeleton who has the power to turn any person with the slightest bit of darkness in his or her heart into a skeleton warrior like himself. The other skeleton warriors are bound to him by a spell, though a few of them have agendas of their own. The villains are opposed by Prince Lightstar/Justin Steele (who has the other half of the Crystal), Princess Talyn/Jennifer Steele (who has the ability to restore skeleton warriors to the flesh), Prince Grimskull/Joshua Steele (an undead former follower of Baron Dark who seeks redemption), and their uncle and mentor Ursak the Guardian. A slight complication for Baron Dark's plan is that the female skeleton warrior Shriek has a lifelong unrequited love for Justin Steele. Despite being a villain in her own right, she does not want to hurt her love interest.