Wilbur Smith - The Dark of the Sun

Bruce Curry is the leader of a mercenary band with the dubious support of three white officers. His mission is to relieve a mining town cut off by the fighting and to retrieve a priceless consignment of diamonds. Ranged against his ill-disciplined unit are bandits, guerrillas and hostile tribes that infest the land. But there is another, even deadlier enemy -- one of his own men...