Because the Night — James Ellroy

Three citizens are butchered during a liquor store holdup. An unstable veteran cop vanishes without a trace. Nothing connects these events except for a nagging hunch in the back of Detective Sergeant Lloyd Hopkins' brain--a sinister foreboding that will lead him through the sin-and-sleaze playground of nighttime L.A. on the trail of a psycho psychiatrist with a talent for terror and mind-control. His gore-soaked journey through Hell will plunge this determined manhunter into the dark heart of madness... and beyond.