Jacob and Marley are best friends who spend every summer together on a quiet sandbar. But one day the boys get into trouble, and only one of them, Jacob, returns from the sea. Now, on the seventh anniversary of this terrible event, Jacob himself disappears without a trace. The police are searching. Old secrets, jealously guarded by local residents, are brought to light. Jacob's mother, Sarah, is sure that no one can be trusted. After all, someone in the shallows knows what really happened to her son. And he will do everything to keep it a secret...