College professor Philip Brainard (Robin Williams) is so absent-minded that he manages to miss his own wedding to colleague Sara Reynolds (Marcia Gay Harden).

The reason Philip forgets is his new invention - Flubber, a high-energy green substance which can bounce great distances, even enabling Philip to fly his car like an aeroplane. However, Philip and Flubber have their work cut out when they discover that Sara has been sweet-talked by Philip's rival in love, Wilson.

Together with Philip's pet robot, Weebo, they set about winning Sara back.