Los Angeles, 1949. Ruthless, Brooklyn-born mob king Mickey Cohen (Sean Penn) runs the show in this town, reaping the ill-gotten gains from the drugs, the guns, the prostitutes and — if he has his way — every wire bet placed west of Chicago. And he does it all with the protection of not only his own paid goons, but also the police and the politicians who are under his control. It’s enough to intimidate even the bravest, street-hardened cop… except, perhaps, for the small, secret crew of LAPD outsiders led by Sgt. John O’Mara (Josh Brolin) and Jerry Wooters (Ryan Gosling), who come together to try to tear Cohen’s world apart.
After growing up during the tumultuous 1960s, ex-Black Panther Marcus returns to his home in Philadelphia in 1976 and reconnects with Pat, the widow of a Panther leader. Marcus befriends Pat’s young daughter and attempts to conquer his demons. Interfering with Marcus’s good intentions are the neighborhood’s continuing racial and social conflicts, as well as old enemies and friends — both with scores to settle.