NEW ORLEANS, 1919. For nearly a decade, a ruthless killer has prowled the streets of this city, breaking into homes in the middle of the night and hacking people to death with an ax. He leaves few clues. Even his motives are unclear. The police are baffled. The killer even writes a letter to a local newspaper--echoing Jack the Ripper from three decades earlier--and claims to be a "demon from hottest hell."But Detective Colin Fitzgerald, a wounded...