This is the year 2000 entry in James Lee Burke's series about Louisiana police detective Dave Robicheaux. As usual, Burke is an unequalled master at putting the reader into a scene, showing the vivid colors, smells, and textures. Also as usual, he puts all the characters in the book through several assorted flavors of Hell; no modern fictional detective suffers from this treatment more than Dave Robicheaux.
In this outing, Dave is trying to assemble evidence to provide clemency for Letty Labiche, a woman on death row who has (apparently) killed a cop that used to abuse her. But soon he and his colorful sidekick Clete run into a lowlife who claims he has information on the foul-play death of Dave's mother years ago. Various other characters appear: the colorful but ficticious Louisiana governor; the Louisiana attorney general; a sociopathic hitman who develops a connection to Dave's daughter Alafair; a dirty cop who used to have a relationship with Dave's wife Bootsie. Everything is resolved at the end, with many of these people becoming deceased along the way.
I notice that they're bringing out a movie based on In the Electic Mist with the Confederate Dead, a previous book in the series. (They've shortened the title to In the Electric Mist.) Dave is played by Tommy Lee Jones, which (to my mind) is just about perfect casting; I've "seen" Dave Robicheaux as Tommy Lee Jones since I read the very first novel long ago. (A previous attempt at a Dave Robicheaux movie, Heaven's Prisoners had Alec Baldwin as Dave; this wasn't as bad as it sounds, but it wasn't great. It's your go-to movie for seeing Teri Hatcher in the altogether, though.)