Arthur has to take the bus to the public pool for his swimming lesson, but while reading a book, he falls asleep on the bus, only to miss his stop. Ending up at the edge of town, Arthur tries to find his way home, while D.W. becomes truly scared for Arthur's safety. Arthur stops at a diner for help, where he talks to a friendly bus driver named Sam, who takes him back home. Arthur loses a to-do list he planned for the summer, and the first day of school is quickly approaching. As summer ends, he feels upset that his friends did fun things and he did not. On the last day of summer vacation, Arthur finds his list taped to his bedroom door and realizes that he did everything he wanted to.