The trailer spotlights cop Jerry Wooters (Ryan Gosling) as he takes the law into his own hands.
The film tells the story of police sergeant John O'Mara, who forms a secret group of LAPD outsiders into a squad to take on Sean Penn's mobster Mickey Cohen.
It is based on the true story of the struggle to free the young Los Angeles from the grip of the mafia.
The Ruben Fleischer-directed movie also features Emma Stone, Nick Nolte, Robert Patrick, Michael Peña, Giovanni Ribisi and Anthony Mackie.
Gangster Squad will open on January 11, 2013.
Ryan Gosling on set: