Arrietty (Bridgit Mendler), a tiny, but tenacious 14-year-old, lives with her parents (Will Arnett and Amy Poehler) in the recesses of a suburban garden home, unbeknownst to the homeowner and her housekeeper (Carol Burnett). Like all little people, Arrietty (AIR-ee-ett-ee) remains hidden from view, except during occasional covert ventures beyond the floorboards to "borrow" scrap supplies like sugar cubes from her human hosts. But when 12-year-old Shawn (David Henrie), a human boy who comes to stay in the home, discovers his mysterious housemate one evening, a secret friendship blossoms. If discovered, their relationship could drive Arrietty's family from the home and straight into danger.