The project is based on the true story of an elite LAPD unit in the 1940s, which was tasked with taking down the crime rackets lead by gangster Mickey Cohen. Michael Peña will portray a young cop who is eager to prove himself to the unit. Sean Penn is portraying Mickey Cohen, while Josh Brolin and Ryan Gosling will play John O'Mara and Jerry Wooters, two of the rare cops who aren't on Mickey Cohen's payroll.
Ruben Fleischer is directing The Gangster Squad from a screenplay by Will Beall, a former LAPD officer. The script is based on an seven-part series of Los Angeles Times articles written by Paul Lieberman in 2008.