While fishing one day in his small rowboat, William Constable catches a glimpse of something unusual in the water. Standing to get a better look, the youngster loses his balance, hits his head on the edge of the boat, and falls unconscious into the water. So begins this exciting tale about two boys and a loveable sea monster named Chessie. Soon after the mishap, William tells his best friend, Tommy, about his encounters with Chessie, and every day the boys row down Heron Creek to play with her (bringing along her favorite snacks--tuna fish sandwiches and Oreo cookies). A cruel, greedy man sees them romping with their secret pet and plots to trap Chessie and sell her for big bucks to movie makers or scientists. The nighttime operation that William and Tommy undertake to save their friend will thrill readers young and old. Middle grades-ages 8-12.