Sera Finn is eleven when she's first brought from the Newberry Children's Home to Lake Ephemeral. She's about to meet a mother she'd never known she had.
She discovers the mysterious valley of Lake Ephemeral, where seven mansions surround a lake and where the children have strange eyes, just like Sera.
She also finds out that the valley is plagued by a massive species of carnivorous plant-named the Coffin Flower, capable of consuming humans. No one can answer Sera the riddle of why the residents stay at Lake Ephemeral year after year and why no one ever leaves.
When one of the children becomes critically ill, the adults don't take her out of Lake Ephemeral to a hospital. Sera begins to suspect that the valley has terrible plans in store for the children and she makes a desperate plan to escape.