A documentary filmmaker and her crew set sail down the Mississippi River to investigate a series of mysterious disappearances, and cling to their slipping sanity as the horrifying truth begins to emerge. Years ago, Elly Thompson was boating down the river with her father when he simply vanished without a trace. Upon learning that he was merely one of many, Elly rounds up a small crew and hires a man named Jack to guide them down the river. But the closer their boat gets to the site of the disappearances, the more unwelcoming the river becomes. Only when their numbers have dwindled and their perception has been distorted will this terrified crew finally learn the answers they've been searching for.