Sunbeam, a young teen, is a spunky, impulsive outcast whose fierce devotion to find her missing twin sister is threatened by a chilling, dark presence. Sunbeam’s twin, Gilda, diappeared five years ago. Worse, Sunbeam never knew her father; he mysteriously left the family. So she lives with her mother, who always references a nameless threat but never answers her questions.

When Sunbeam finds a mysterious Golden Key, she and her loyal horse, Whitewing, are catapulted into the Depths of Cypress: a shadowy forest where she discovers traces that propel her forward. Along the journey, she realizes she is only a step from death after she finds clues about the island’s hidden secrets. Whitewing sticks close by her side as they try to escape the cryptic Depths alive–and most of all–uncover the truth about Gilda.