Longtime class pets Leo the tuatara and Squirtle the Florida box turtle live in a fifth-grade classroom at a Fort Myers elementary school. During a parent-teacher conference, the pregnant fifth-grade teacher Mrs. Salinas announces her maternity leave. As the parents come to express their displeasure with the substitute teacher whom Principal Spahn has selected to cover for Mrs. Salinas, Leo overhears one of them say that tuataras live to be 75 years old and despairs when he realizes he is 74 and has not accomplished his dreams of going to the Everglades. The next day, the strict substitute Virginia Malkin arrives and is quickly loathed by the students.