Ryota is an unpopular writer although he won a literary award 15 years ago. Now, Ryota works as a private detective. He is divorced from his ex-wife Kyoko and he has an 11-year-old son Shingo. His mother Yoshiko lives alone at her apartment. One day, Ryota, his ex-wife Kyoko, and son Shingo gather at Yoshiko's apartment. A typhoon passes and the family must stay there all night long.

14-year-old Arrietty and the rest of the Clock family live in peaceful anonymity as they make their own home from items "borrowed" from the house's human inhabitants. However, life changes for the Clocks when a human boy discovers Arrietty.