For generations, Sybaline's family has lived in a magical valley in the Appalachian mountains, helping the magic grow the land. But now the government has ordered them to relocate; their valley is needed to create a dam for electricity. In one week, their home will be flooded.

Sybaline can't imagine life without her home and without the magic. Stopping the dam proves to be impossible; the government is too big and too strong. She takes the only choice left: she stays. Using her magic, she builds a wall, and as water floods the valley, it covers her house, leaving her living beneath the lake itself.

But there is a consequence to using magic in such a way, one that will transform both herself and the friends who end up trapped beneath the water with her. If she can't find a way to escape the prison she's created, both she and those she loves will end up staying in the watery grave of the valley forever.