After Melanie Delgado lost both of her parents, she was taken in by the Augustines, a wealthy and Lumen family in the city of Light Haven. She formed a close bond with their daughter, Taren, whom she was destined to protect from wraiths living in the Sliver. But after a ritual that would've created a bond between the two girls failed, Melanie became an ineffective Mask and has grown up being ridiculed by Lumen and Masks alike - including Taren.
The bond only lasts until Taren turns eighteen and with eight months to go, Melanie is counting down the days until she's free. All she wants to do in the meantime is hunt wraiths and spend time with the Mask leader, Michael Hensley, without having Taren around to mess that up for her - which gets complicated once Clayton Reiner, hottest guy in Light Haven and a Lumen at that, takes an interest in her.
But when a Decoy goes missing days before her freedom and Melanie begins to have vivid dreams about the Sliver, she discovers something shocking about the Lumen community of Light Haven: the light is better at hiding secrets than the shadow.