Pegasus Descending — James Lee Burke

When a nice young woman named Trish Klein blows into Louisiana passing hundred- dollar bills in local casinos, detective Dave Robicheaux senses a storm bearing down on his new life of contentment.... Twenty-five years ago, lost in a drunken haze in Florida, Robicheaux was too far gone to save his friend and fellow 'Nam vet Dallas Klein, murdered in cold blood for gambling debts. Now, the arrival of Dallas's daughter opens a door locked long ago, and extracting her motives points Robicheaux to the suicide of a local "good girl" pulled into a vortex of power, sex, and death. It's Robicheaux's most personally painful case--a roller coaster of passion, surprise, and regret--and it may be his deadliest.