Arrietty longs for adventures, but the world can be a dangerous place for one so small. She and her family live hidden beneath the floorboards of a house, borrowing the things they need from the humans who live inside. When Arrietty is discovered by a human boy named Shawn, her world is no longer secret and her family is in danger. If Arrietty can trust Shawn to protect her, she might discover a friendship she never imagined possible.