Aging motorcycle racer J.W. Wyatt is approached by rich industrialist and racing enthusiast Packard Gentry to endorse his own custom-designed cycle, the Sidewinder 1. Wyatt brings in a team, including young and reckless Digger, to test and augment the prototype bike. When Gentry dies in a motocross accident, Wyatt must persuade Gentry's unenthusiastic and corporate-minded sister Chris to continue backing the project.