Marty is a 19 year old pioneer woman, recently married. She goes west with her husband Clem, hoping to start a new life. But Clem unexpectedly dies, and Marty finds herself alone, two months pregnant. Clark Davis, a widower, offers her a marriage of convenience: she needs food and money, and he needs someone to take care of his daughter Missie. She accepts his proposal as a temporary solution.
In the quiet waters of the Mississippi, body parts are being discovered. No one knows what is behind it all, until a huge man eating bull shark turns up. This bull shark is different, as it can breath in fresh water, making a deadly encounter between anyone who comes before it. John Sanders must now try and reach the surface, with his ex-wife and whilst being held hostage.