Dusty Rhoades is a winner at racing cars but is unable to win the consent of truck manufacturer Pat MacMurran to marry his daughter Virginia. Dusty strikes a bargain with Pat to make his Parko trucks famous in exchange for Virginia's hand in marriage. After several dismal attempts, Dusty hears that the Cabrillo dam is threatening to break and flood the valley. Recruiting race car drivers to drive the trucks, Dusty loads the fleet with sand and explosives, travels impassible roads, reaches the dam, drives the truck into the breach and saves the valley, making the Parko trucks famous. On the spot, Pat offers Dusty Virginia, and the position of manager.