Mei and Satsuki are having a wonderful time working in Granny's vegetable garden while their dad is away at work. But one afternoon there's bad news from the hospital where the girls' mother is recovering. Mei decides to go visit her mother alone...on foot!

When Satsuki realizes her little sister has disappeared, she takes action. But is it too late? Satsuki scours the forest and the countryside, but the search for Mei doesn't look hopeful--until Totoro steps in. With a little help from the forest spirits, including a wild ride in the Cat Bus, the sisters learn the importance of trusting in one another and hoping for the best.