A lighthouse stands at the edge of the worlds, guiding voyages between them and maintaining the balance of the universe. When the Lighthouse Master vanishes without warning, his duties pass to his assistant, Dillon Havelock, and though Dillon shares his mentor’s power—the greatest magic in all the realms—he utterly lacks the charisma and charm needed to navigate the tumultuous political affairs of each world. And despite Dillon’s every effort to find the Lighthouse Master, the trail has quickly gone cold.

Until disgraced socialite Cassidy Leighton is shipwrecked upon the Lighthouse’s island. She comes from a world with no knowledge of other realms or magic. To her, the Lighthouse is a romantic figment from her father’s stories, and she gave up on such whimsical, childish notions the day her father was murdered.

Except the other worlds are real. Magic is undeniably, marvelously real. And somehow, her father’s death is connected to the Lighthouse Master’s disappearance.

In an entanglement of secret societies, fantastical wanderlust, and grandiose destiny, Dillon and Cassidy must find the key that Cassidy’s father died to protect . . . . before each of the worlds begin to fall.