L.A. Confidential by James Ellroy

Christmas 1951, Los Angeles: a city where the police are as corrupt as the criminals. Six prisoners are beaten senseless in their cells by cops crazed on alcohol. For the three LAPD detectives involved, it will expose the guilty secrets on which they have built their corrupt and violent careers. The novel takes these cops on a sprawling epic of brutal violence and the murderous seedy side of Hollywood. One of the best crime novels ever written, it is the heart of Ellroy's four-novel masterpiece, the LA Quartet, and an example of crime writing at its most powerful.