Mike Lamon is fifteen, a surfer and football player, and eager to buy a motorcycle with $600 he has saved by picking farm produce. But his father is so old-fashioned that he refuses permission until Mike has learned the rules of the road. The boy's older brother Pat meets a former prospector with a bright green dune buggy for sale—for exactly $600. The cold California winter that follows is a busy one. Mike must not only learn to handle his new wheels, but to negotiate life with his increasingly testy father, to enter the local dating scene with the prospector's granddaughter, and to face the fact that Pat may soon be drafted and sent to Vietnam.