'Prison Break' Big Bad Robert Knepper Goes Good Guy on 'Hawaii Five-0'

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Fresh off of a one-episode gig playing the bad guy of the week on NBC's "The Blacklist," Robert Knepper will find himself on the other side of the investigation on an upcoming installment of CBS's "Hawaii Five-0."

During a junket interview in Beverly Hills today for "Mob City," the Frank Darabont-created L.A. noir three-week-event series coming to TNT in December, the former "Prison Break" baddie who plays mob enforcer/psychopath Sid Rothman in "Mob" was discussing whether he ever worried about consistently being cast as a villain when he let slip that he will be saying aloha to McGarrett and the gang come early 2014 as a member of the long arm of the law. (Coincidentally, TNT airs "Hawaii" Thursdays in syndication.)

"I'm playing an internal affairs guy. Every season they go after one character and they devote the whole episode to that character. Mine is with Daniel [Dae Kim], who plays Chin Ho Kelly. It is basically a two-hander, just the two of us through the whole thing," explained Knepper, adding that going good takes more focus and energy on his part. "I'm playing a straight and narrow cop. In my head, I'm going, 'OK, I gotta make it interesting.' Whereas if I play a bad guy, I never have to think about that."

[Related: Ed Burns: 'Mob City' Made Me Fall in Love With Acting Again and Led to My Dream Project]

Knepper relishes the opportunity to wear a white hat from time to time but has also come to terms with being a go-to guy for criminals, cult leaders, and killers. "For years, I was like, 'I don't want to play the bad guy," [because] I had a niece who was born in 1990, and I didn't want her to see me playing a bad guy. I called it the Megan factor. Then I woke up. There are a lot of guys in their careers who played heavy characters, like Robert Mitchum, Jack Palance, all the horror movie guys like Boris Karloff. They did just fine with great careers and had families. So what if I was playing all bad guys? Whatever keeps them in their seats. I have a great f---ing career...

"Especially after T-Bag, people say, 'Are you worried about being typecast?' Acting is a really f---ing hard business. It's impossible," he continued, also noting that he just finished playing a "normal" architect and ex-husband in the film "Ride" opposite Helen Hunt. "[But] I'm loving the path. I get to travel. I get to buy my 11-year-old son Kings tickets. I get to do amazing things."

Ed Burns, who was partnered for press with Knepper, backed up his just-do-it philosophy. "At a certain point, you gotta make your annual nut. You need a job," Burns joked before admitting to location envy, as "Hawaii" shoots in the titular state. "C'mon, [that's a] great gig."

Watch a sneak peek of "Mob City":

Knepper joins the growing list of notable Season 4 guest stars, which already includes Carol Burnett (as McGarrett's aunt Deb), Daryl Hannah, Corbin Bernsen, Rebecca De Mornay, Jorge Garcia, Tim Daly, and singer Nick Jonas, who played a computer hacker.

In other "H50" news, CBS announced that Chi McBride, first seen in the Season 4 premiere last September, stripped down to his skivvies, will now be booking 'em with Danno and company as a series regular. McBride plays Capt. Lou Grover, the head of SWAT on the island, who recently relocated his family from Chicago to Oahu. Grover is based on a character of the same name from the original tropical cop series.

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"After his first guest spot, we knew we had something special here with Chi," executive producer Peter Lenkov said in a press release regarding McBride's promotion. "He just fit seamlessly into the fabric of 'Hawaii Five-O,' and viewers are enjoying the spirited, if sometimes antagonistic, interaction between him and McGarrett."

McBride seems thrilled to extend his stay in paradise, according to his official statement. "I know this sounds corny, but the only thing I ever wanted in my career was to be on CBS, the home of my idol Jackie Gleason," McBride said. "I finally made it to the Tiffany network on 'Golden Boy,' shooting scenes on the same stage where 'The Honeymooners' was filmed. CBS graciously invited me to be a member of the cast of 'Hawaii Five-O' and it's been wonderful. The cast, crew, and production have been so welcoming to me. My love affair with CBS continues."

"Hawaii Five-O" airs Fridays at 9 p.m. on CBS.

"Mob City" premieres Dec. 4 at 9 p.m. on TNT.