Madelyn is a tenacious young turtle who can't seem to find any other turtles who look like her She's a special turtle called a terrapin, and she lives in the Chesapeake Bay. Feeling lonely and sad, Madelyn decides to go traveling and find other turtles like her, but at first, she only runs into trouble.

She meets a grumpy snapping turtle who is anything but encouraging. She comes across some serious Bay pollution where she meets a much kinder, more welcoming oyster toadfish. Madelyn also meets Jurgen the sturgeon, but she keeps on moving, in search of an elusive terrapin to call...