Charlotte Richards' carefree world turns upside down on her eleventh birthday, the day her beloved papa dies in a spring storm on Lake Michigan. Without the persistence of fifteen-year-old Seth Trevelyn, son of South Manitou Island's lightkeeper, she might never have smiled again. He shows her that life goes on, and so does true friendship. When Charlotte's teacher invites her to the World's Columbian Exposition of 1893, Seth signs as crewman on the Martha G., carrying them to Chicago. Together, Seth and Charlotte sail the waters of the Great Lake to the very portal of the Fair, and an adventure they will never forget. While there, Seth saves Charlotte from a near fatal accident. Now, seventeen and a man, he realizes his friendship has become something more. Will his feelings be returned when Charlotte grows to womanhood?