A couple driving along a deserted road to a lake almost run over a young
man, a student, who flags down the car almost too closely. The driver is a
self absorbed husband, the woman his pretty, irritated wife. They take him
along and the husband, out of the sheer patronizing will, invites him to come
sailing on their boat. During the boat ride there is clash of personalities. The
boy has a habit of playing with a switchable blade knife. The husband is a
self-made man and delights in showing up the boy. In an argument he
knocks the boy off the boat. The couple thinks he has drowned and the
husband swims to shore for help. But the boy has hid behind a buoy and
comes aboard to seduce the wife. She finally brings in the boat and assures
her husband the boy is alive and that she has cheated on him.