House of the Rising Sun

This is the 4th in James Lee Burke's Holland family series that feature Hackberry Holland. We meet up with Hack when he has been desperately trying to find his estranged son, Ishmael, in the middle of the Mexican Revolution in 1916. He has done things he would rather not think about and is now lost in the desert, bootless, weaponless, and on the run using a horse stolen from Pancho Villa's army, when he stumbles upon a bordello with a hearse sitting out front. He is captured by the Mexican soldiers who have taken the house and killed several of Ishmael's cavalry company of black soldiers.  Hack escapes and blows up the weapons that were hidden in the hearse after rescuing a gold-embellished onyx goblet, rumored to be the Grail. The madame, Beatrice DeMolay, has a profound impact on him and will enter the picture again as the story goes on.  He does not find Ishmael, but keeps searching and writing him letters.
Two years later, in 1918, we join Ishmael at the Battle of the Marne and get vivid descriptions of the insanity that is war. He is grievously wounded and sent back to the U.S. In the meantime, we get some background on Hack's meeting of Ishmael's mother, Ruby Dansen, their separation and Hack's thwarted attempts to reconcile with her and reunite the family. His efforts fail largely as the result of his on-again, off-again wife's (Maggie Bassett) destruction of vital communications between Ruby and Hack. Ruby and Ishmael are left thinking that Hack promised to come get them and then never showed.  Ishmael thinks his father, "Big Bud," abandoned them.
Beatrice, Ruby and Maggie will wind in and out of Hack's life as he tries to find his way forward to seeing his son again. Another major player in this drama is the Austrian arms dealer, Arnold Beckman. Both the hearse full of destroyed weapons and the cup were Beckman's, and he is determined to get it back at any cost. Beckman aligns himself with Maggie and kidnaps Ishmael from a military hospital to hold hostage in order to get the Grail back. Beckman is the embodiment of amoral evil, but Hack also has a demonic destructive force inside him that either drives him to drink self-destructively or lay waste to those he believes do wrong.
Although, the ending is satisfying, the level of darkness in the book was often times nearly overwhelming, leaving me wondering if any good could come out of the guilt and self-loathing that Hack evidences. Burke is of course an outstanding writer--his prose is second to none. But this is not an upper of a read, even at the very end.