In the summer of 1839, British spymaster Sir John Oldmixton asks Benjamin January to identify an Englishman found dead in a New Orleans canal. January refuses until evidence connects the corpse to a murder he failed to solve in Paris during the July Revolution nine years earlier.
The two cases join political exile, hidden treasure and the fate of a woman endangered by the old crime. January must reconstruct events from the fall of the Bourbon monarchy while protecting his family in New Orleans, where the people responsible for the first killing have both motive and opportunity to commit another.