Anise is on the run from a cycle of abusive relationships, so when the offer comes to take up residence in a remote historic cabin on an island in an even more remote lake as a caretaker, she dives at the chance. But the job comes with some strange rules—and as Anise and her nine-year-old son come to terms with the isolation and eeriness of the cabin, they sense that someone—or something—else is hiding out there too, beneath the water.