Still reeling after discovering she's a witch, Mia learns that sixteen years ago she was born with The Arx-a force-field so coveted that dark witches would stop at nothing to steal it. With her brother Dino at her side, she flees to the Glass Castle in hopes of reversing the sinister fate foreseen by their aunt. Despite Dino's warnings, Mia seeks comfort from Colt, the alluring Hunter charged with protecting her. But just as Dino begins to trust Colt, the siblings are blindsided by an unnerving suspicion: can a Hunter ever be trusted?