The oceans are dying. In an effort to provide sustainable tuna stocks, genetically engineered humans have been reconfigured to live at sea, using dolphins to herd large tuna schools. Olga is one of these shepherds. Independent fisherman are having a hard time catching fish and Toivo is among the best because he has a pair of dolphins that he talks to and they help locate fish for him. Troubles erupt when Toivo finds a raft of murdered shepherds and now he's a target along with Olga and her shipmates. When fate brings them together they will have to find a way to survive against a drug cartel determined to eliminate witnesses.