Phillip Brainard(Robin Williams), who is a professor at a college and a small time worker in his own basement, is trying to create a great invention. Unfortunately he always failed to invent something, but he is so obsessed about it that he even puts off his own wedding to his fianc?e, Sara(Marcia Gay Harden). One day, he finally invents something that works, this substance can cause even the heaviest things to bounce in the air, 'flying rubber', but Brainard called it "Flubber". However, he sees Sara going out with another professor from another college and several criminals trying to rob him. So, Brainard has to find out a way to defeat the criminals and to get back his Fiancee. Hopefully, Flubber can help him.