The year is 1924.
Sam Lacy, tough as nails robbery/homicide detective follows his own unique code of conduct within the racist and corrupt Los Angeles Police Department.
Edward Bixby, a brilliant man fascinated by anything scientific, assists with the forensic aspects of Sam's investigations but his work must stay on the down low since the LAPD would never hire a black man for anything as important as detective work. Sam's sister, Susan, widowed mother and sharpshooter, is the most important person in his life. And Lonny, Sam's handsome, cynical partner, sports a cavalier attitude that hides a troubled past.
Together they must solve the murder of Sam's old flame and deal with a ruthless and powerful predator who victimises vulnerable young Chinese immigrants. Their story takes place in the movie capital of the world, a city that attracts hustlers, wide-eyed innocents and cold-hearted killers; a City of Angels.