Who can solve this circular mystery? Young Per loves to play games. When she visits her uncle Sir Cumference and her aunt Lady Di of Ameter, they teach her a new game. But the game has a hidden message that points to a mysterious message that points to a mysterious island...Per and her cousing Radius set sail for the Isle of Immeter. Can the cousins unlock the secret of Immeter before the fearsome sea serpent finds them? Math skills taught include finding the area and perimeter of a rectangle and a circle. Introduces an underlying concept of calculus — using straight lines to measure curves.