On the isolated island of Brack, the people live by an ancient bargain: every year, a sacrifice must be made to the Glimm, the creature that haunts the salt marshes.

Eight years after the monster spared her, 16-year-old Lotta tends the Council’s sacrificial horses and keeps her distance from the villagers who whisper about her fate.

But something is stirring. The island is dying. It hums beneath her feet, and a song threads through her dreams. Is the Glimm calling Lotta back?

A chance encounter with Moss, a village outcast, will change both their lives, and the fate of the island, forever. To uncover Brack’s deepest secrets, Lotta and Moss will need to trust each other and risk everything they hold dear.

Because on Brack, monsters come in many forms.