Crusader's Cross (Dave Robicheaux #14) by James Lee Burke

In Crusader's Cross, a deathbed confession from an old schoolmate reminds Dave Robicheaux of a girl he once knew, sending him on a hunt for her whereabouts. Her name may or may not have been Ida Durbin. It was back in the 1950s, when Robicheaux and his brother Jimmie met her on the beach. She was a pretty girl and Jimmie fell for her hard--not knowing she was a prostitute with ties to the mob, and that she meant big trouble. Luckily, she disappeared from their lives without a trace.

Now, decades later, Robicheaux is asking questions about Ida Durbin, and a couple of red-neck deputy sheriffs make it clear that asking questions is a dangerous game. With a series of horrifying murders that somehow seem connected to the past, and the sudden appearance of Valentine Chalons, a troubled and deeply alluring young woman, Robicheaux is soon involved not only with the powerfully wealthy Chalons family but with the cold-blooded New Orleans mob and its lethal history...

Brilliant, brooding, and filled with the author's signature lyricism, Crusader's Cross is "Burke at his most eloquent"