Deadly Shoals

Wiki Coffin plays many parts on the U.S. Exploring Expedition—-sailor, linguist, navigator, and, as half-Maori, cultural go-between. But then the brig Swallow reaches the coast of Patagonia, an area infamous for its rough gauchos and revolutionary spirit, and he must take on his other role, that of agent of U.S. law and order.
A New England whaler shows up, desperate to find the devious trader who has cheated him of a thousand dollars and a schooner. Wiki is assigned to find the missing ship, only to follow a trail of clues to a dead body, half-buried in a hill of salt, its skull picked clean by vultures. The adventure unravels in the impoverished village of El Carmen de Patagones, where the threat of French invasion is imminent, and business is at a standstill under the orders of General de Rosas, the tyrant of Buenos Aires.
Wiki must risk both life and reputation in pursuit of a vicious and determined killer who has set his sights on another target: the U.S. Exploring Expedition itself.