Nobody has an easy time of it in the costume actioner Shark River. Wanted for murder, Clay Webley (Warren Stevens) and his wounded cellmate Curtis Parker (Robert Cunningham) hack their way through the Florida swampland. With the help of Clay's brother Dan (Steve Cochran), Clay is able to elude the authorities, but Parker dies of a snakebite. Subsisting on alligator meat, Dan and Clay make their way to the tiny cabin inhabited by widowed Jane Daughterty (Carole Mathews), her mother-in-law, and her son Johnny (Spencer Fox). The brothers rest here awhile, formulating plans to cross the Gulf of Mexico and head for Cuba.