Identical twins Sonja and Charlotte are musical prodigies with extraordinary powers. Born on All-Hallows-Eve, the girls could play music before they could walk. They were found one night by Tatty, the Tattooed Lady of the circus, in a pail on her doorstep with only a note and a heart-shaped locket. They've been with Tatty ever since, roaming the Outskirts in the circus caravans, moving from place to place.
But lately, curious things have started to happen when they play their instruments. During one of their performances, the girls accidentally levitate their entire audience, drawing too much unwanted attention. Soon, ominous Enforcers come after them, and Charlotte and Sonja must embark on a perilous journey through enchanted lands in hopes of unlocking the secrets of their mysterious past.