Young Pete Lender Bradley Pierce notices small items vanish from the family home and explains to his parents Joe Lender Aden Gillett and Victoria Lender Doon Mackichan that these disappearances aren’t mere accidents. Behind the walls and under the floorboards, a tiny family of Borrowers—the Clock clan led by Pod Clock Jim Broadbent—has been living unseen, discreetly lifting objects that humans simply chalk up to a misplacement. The Lenders’ trouble begins to mount when lawyer Ocious P. Potter John Goodman arrives, claiming he cannot find the will of Victoria’s late aunt Mary Alabaster, the document that would validate the house as the Borrowers’ rightful home, and with that claim he schemes to demolish the house and replace it with condos.
Pod Clock Jim Broadbent and his children Arrietty Clock Flora Newbigin and Peagreen Clock Tom Felton venture through the kitchen, attempting a careful “borrow” of a battery to sustain their tiny world. Arrietty indulges in a brief ice-cream indulgence from the freezer and, in a perilous moment, gets trapped inside. Pod rescues her with a swift move through the ice dispenser, but a gadget of his is left behind, a clue that the humans might someday uncover. Arrietty, venturing out alone again, is soon captured by Pete, who—though curious—begins to see that the house is more than a place to hide. The two form a wary bond, and Pete explains the looming threat: without the will, the house will be razed.
Arrietty warns her family, and, against his better judgment, Pod concedes to Pete’s plan and allows the Clocks to ride along on the Lenders’ moving truck, hoping to reach safety at a new residence. Pete returns Pod’s gadget, rekindling trust between the human and Borrower worlds. As the truck pulls away, Arrietty and Peagreen slip off the moving pile and struggle back toward the house, unsure where their fate will land them.
Potter soon arrives at the property, and the truth about his deception comes to light: Victoria Alabaster had indeed hidden her will—inside the very walls of the house. He finds the document in a concealed safe and prepares to burn it to erase any trace of the Borrowers’ claim. Arrietty and Peagreen escape with the will, while Potter summons Exterminator Jeff Mark Williams to “exterminate” the Borrowers. The confrontation escalates quickly, with Mrs. Potter’s spite shining through as a police Officer Steady Hugh Laurie and the local constables respond to the uproar. In a shocking turn, Potter is sprayed with caustic foam and electrocuted, his plan foiled, though he remains determined to press on with his demolition scheme.
The pursuit spills into the dairy, where Peagreen accidentally tumbles into an empty milk bottle and is captured for processing. Potter, Jeff, and Jeff’s flatulent bloodhound Mr. Smelly close in, while Pete, Pod, and Homily Clock Celia Imrie scramble to keep the document—now the key to their future—out of Potter’s hands. Spiller [Raymond Pickard], a Borrower living on the city streets, helps Arrietty reach the dairy, and Pod rescues Peagreen from the belt of the assembly line. Potter’s cruel plan intensifies as he traps the Borrowers, attempting to drown them in liquid cheese, but Spiller taunts him, and the would-be tyrant ends up trapped in a dangerous machine—an act that seems to mark his downfall.
Pete arrives just in time to rescue the Clocks, and Jeff, realizing Potter’s true motives, has a change of heart and drives them toward City Hall to halt the demolition. Potter’s path is blocked by a dizzying array of mistaken directions from a City Hall clerk, and a wild chase ensues. At the demolition office, Potter confronts the trio again, only to be outmaneuvered and captured. The Borrowers, led by Pod, along with Pete and Officer Steady, spring their final plan into action. Spiller arrives with an army of Borrowers to subdue Potter, who is warned—on behalf of every Borrower—about the consequences of his greed.
With the will secured and the law on their side, Potter is arrested, and the Lenders reclaim their home. The Clock family returns to their living space, now fully supported by Pete’s help and the scavenging Borrowers they’ve befriended, including Minty Branch Bob Goody, Swag Moss Patrick Monckton, and Dustbunny Bin Andrew Dunford. Arrietty and Spiller sneak away for a playful ride on Spiller’s aerosol-paint-propelled roller skate, a small moment of whimsy that caps off their hard-won triumph.
In a final, comic coda, Potter, now stripped of his power, entertains the absurd idea of the Borrowers’ existence as he faces mugshots and a city-wide chorus of laughter from cops and convicts alike. The film closes on a hopeful note: the Lenders move back into their home, the Clocks remain integrated in their lives, and Pete’s friendship with the Borrowers continues to grow, a quiet reminder of the delicate balance between human and tiny worlds.
