When Matilda Benson solicits the help of Perry Mason, her request seems simple enough: cruise to a gambling ship moored just beyond the twelve-mile limit and buy back the IOUs signed by Miss Benson's niece. But after Mason reaches the floating casino, he discovers problems aplenty—most notably the ship's owner with a bullet hole through his head. Strangely enough, Matilda and her niece are also on board that night…when someone tosses a gun over the railing. Does Perry Mason's client have something to hide?