Despite one failed invention after another, young Henry knows in his heart that he's a brilliant inventor. Against the advice of his friend, Franklin, Henry conducts his biggest experiment ever, but succeeds only in blowing up the local schoolhouse. Expelled, Henry continues to believe there's a living to be made from inventing weird and wonderful labor-saving machines. But his machines cause more trouble than they're worth and after one of them goes berserk, wrecking Franklin's family's laundry business, Henry becomes an outcast. A near-tragedy in Franklin's family gives Henry the opportunity to try one last experiment and save the day, but can he get it to work?