Nigel, Bruce and St Helenian Jimmy Fowler risk their necks by accepting a ride aboard a motor yacht, the St Valery, for their return to Cape Town. The owner, Barry Jones, wants to make a detour to see the terrifying Namibian Skeleton Coast where numerous ships have come to grief, including the Dundee Star on which Barry's father worked during World War Two. Aboard the wreck is a cache of diamonds, and Barry knows just how to get it, and nothing, it seems, will stop him!This desperate adventure takes the boys to the edge of danger where they fight the most dangerous of the world's deserts with its mysterious plant and animal life, the weird Welwitschia, the grotesque elephant's foot, the desert lions, the brown hyena and the Namib sidewinder snake.They even encounter a galleon several kilometres inland of 'the coast that walks'! All the while, they are dogged by the presence of Isaacs and Lambert.