Out of the corner of his eyes Biggles saw Dick go overboard and disappear under the foam, but he could do nothing to help him. Indeed, as he fought to keep the flying-boat under control, it seemed certain that during the next minute or two the others must join him. Ashen, he looked at Algy. ‘Jump when she hits!’ he cried, in a shrill, strangled voice, and dived deliberately at the rocks. Biggles, Algy and Ginger help a young lad evade a violent thief and find themselves plunged into a dangerous treasure hunt searching for a long-lost pirate hoard of gold in the Caribbean.