Crime drama set in the 1940s and '50s in Los Angeles inspired by the real life story of vicious mob boss Mickey Cohen and the LAPD officers who tried to bring him down. After moving to LA from the East Coast, Cohen (Sean Penn) has taken control of the town. A force to be reckoned with, he not only has his gang to do his bidding but a number of policemen and politicians are also under his command. Police Chief Bill Parker (Nick Nolte) instructs Sergeant John O'Mara (Josh Brolin) to wage war against Cohen and his men. With only a small squad which includes his colleague, Jerry Wooters (Ryan Gosling), O'Mara attempts to regain control of the city. Meanwhile, Wooters gets involved with the mobster's girlfriend, Grace Faraday (Emma Stone), which, if discovered, will only serve to enrage Cohen further.