Entertainment Tonight.Benjamin McKenzie marks his return to TV tonight in "Southland," a gritty police drama set in Los Angeles.

Ben, who last played the Ryan Attwood, a down-on-his-luck kid who is taken in by Sandy Cohen (Peter Gallagher) on "The O.C.," now plays the opposite side of the coin. His new character, Ben Sherman is a rich kid who forsakes college to join the L.A.P.D.

"I've always thought of him as someone who is incredibly ambitious, who is incredibly focused and wants to leave his mark," the Texas-born actor says. "He chose to start off in law enforcement at the street level in order to go his own way. His father [a high-powered defense attorney] is doing something that is almost completely antithetical to what he is doing."

"Southland," from Emmy Award-winning producers John Wells, Ann Biderman and Chris Chulack is a raw and authentic look at a police unit in Los Angeles that takes viewers inside the lives of cops, criminals, victims and their families.

To give the series its sense of reality, Chick Daniel, an ex-LAPD, ex-SWAT officer, and Sheila Daniel, also ex-LAPD, were hired as technical advisors and to train the actors.

"We've hung out a lot with cops," Ben adds. "Chick and Sheila walked us through all sorts of things -- handcuffing, we went to the gun range, fired the weapons that are appropriate for our characters. We've also had the opportunity to do ride-alongs with cops all over L.A. from the valley to Hollywood to southeast and south metro L.A."

"Southland" also stars Michael Cudlitz as John Cooper, a seasoned Los Angeles cop assigned to train young rookie Ben Sherman, Regina King, Tom Everett Scott and Shawn Hatosy.

"Hopefully, this show will capture the zeitgeist at the moment, which is a little dark. We're in a tough time economically. L.A. is not immune from that," Ben says. "L.A. is, in my view, the quintessential American city of the 21st Century in that it's big, crazy and wild. You have extreme wealth knocking up against extreme poverty, and you have all sorts of ethnicities and cultures represented. L.A. is the perfect place to set a show like this."

"Southland" premieres tonight at 10 p.m. on NBC.