By 1867 Doc Carlile is beginning to make a name for himself as an adventurer and an agent. He accepts an offer from a rich American businessman to secure a cargo of stolen saltpeter from the Peruvian Atacama Desert, now stashed in a Panamanian warehouse since the end of the Chincha Island War. But he finds that others are interested, it's not the big secret that he was told it was. In an unstable world, this substance which is crucial for the manufacture of gunpowder is sought for by many nations. The more he finds out, the more it seems he is being steered into a trap so that his employer can obtain the saltpeter for free and become even richer. As usual, the Doctor develops a plan to outwit all the factions involved, making off with the valuable cargo in his own possession. Riches become rags though, and he ends up a prisoner in Spanish Cuba. Embroiled in Spanish politics with a beautiful Spanish woman, on an island heading quickly toward revolution leaves Doc Carlile facing a firing squad. And worse. Unless a Taino talisman can help him make a clean getaway.