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.

Ashitaka, a prince of the disappearing Emishi people, is cursed by a demonized boar god and must journey to the west to find a cure. Along the way, he encounters San, a young human woman fighting to protect the forest, and Lady Eboshi, who is trying to destroy it. Ashitaka must find a way to bring balance to this conflict.