What's the Isle of the Lost?

(Another AU of my Descendant story) Harmony Dust. The adopted daughter of Alastor and Angel Dust. Two of the most famous demons in Hell. Harmony has been sheltered in her aunt Charlie's hotel her whole life not knowing where she came from or why she can do some of the freaky stuff she does. She loves her life and family but when she hears of a proclamation given by a prince in the land of the living she can't resist but check it out for herself. Will she be excepted or will the fact that she was raised in Hell and looks exactly like one of the most powerful Disney villian make everyone wish she stays in Hell forever.