For Mara's 12th birthday her brother, Joe, takes her from their home in St. Louis, Missouri to a flea market in Hannibal. They board a paddle wheel steam boat that shows the two a good time, but also an adventure. When they finally reach Hannibal and the flea market, Mara immediately heads out in search of the perfect tea set that she has been dreaming of for two years since Joe made her a tea box of her very own.