The Hollywood Reporter said the film is based on Paul Lieberman's seven-part Los Angeles Times article about the anti-organized crime unit run by the Los Angeles Police Department in the 1940s.
Enos would play the wife of Josh Brolin's character, John O'Mara, who was one of the few police officers of the era not working for gangster Mickey Cohen, who is to be played by Sean Penn, the report said.
The cast includes Michael Pena, Anthony Mackie, Giovanni Ribisi and Ryan Gosling.
Emma Stone, Gosling's co-star in the current release "Crazy Stupid Love," is also in talks for a role in "Gangster Squad," the entertainment industry trade newspaper said.