Benedict (David McCallum) and Tracey Van Der Byl (Hayley Mills) are the offspring of wealthy Hendrich Van Der Byl (Bill McNaught), who owns and operates Van Der Byl Diamond Mines, one of the smaller yet still very lucrative diamond mining operations in South Africa. Benedict and Tracey grew up with Johnny Lance (Jon Cypher), who Hendrich brought into their house when orphaned and has treated him like another son which Benedict has always resented. While Benedict is a ne'er do well who spends his time chasing women, and on the side steals a diamond here and there from the company to give to whomever his female companion at the time, the current being Johnny's gold-digging wife Ruby (Volenté Bertotti), Johnny, who has overshadowed Benedict all of their lives, has learned the business, and is one of the most respected diamond men in the country. With what Johnny believes is a large cache of diamonds sitting within the reef at Thunderbolt Gap which the larger mining operations have the rig