In the middle of spring cleaning at the apartment building, some pipes burst, so the Doorman must send a reluctant Hundley off the country with George and the Man in the Big Yellow Hat. Hundley is forlorn, so George decides the mutt needs a case of spring fever. Try as George might, he doesn't succeed in infecting his friend. As a big day of hot-air balloon races arrives, Hundley discovers his roots, and it just might lead to his having a good time in spite of being homesick.