Original showrunner Frank Darabont and original series star Jon Bernthal are now both veterans of "The Walking Dead," but their collaboration on the AMC drama was such a positive experience that Darabont lined Bernthal up for his next project while he was still playing out his last days as doomed cop Shane.

"Oh, literally, I was on the set of 'The Walking Dead,'" Bernthal tells Yahoo TV. "Frank and I, after he left, we stayed in very close communication. He just called me up and said, 'Hey, pal. I've got something for you that I'm writing, stay available. Don't take another TV show.'

"I said, 'You got it, buddy.' I had no idea what it was. The show could have been about anything. As far as I was concerned, the chance to work with Frank again was all I needed to hear. It was just an unbelievable honor."

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That show is TNT's 1940s-era crime noir series "Mob City," created by Darabont after he read John Buntin's nonfiction book "L.A. Noir: The Struggle for the Soul of America's Most Seductive City." Bernthal, who's also busy on the big screen this month with roles in "Grudge Match" and "The Wolf of Wall Street," tells Yahoo TV about his Joe Teague, a cop with a lot of secrets, about the payoff that awaits fans of the "slow-burning" drama, and about how he won't let his "Walking Dead" pals give him spoilers about his old show.

Joe Teague is one of the most mysterious characters on the show. Is it safe to assume we're going to find out he's been holding on to a lot of secrets?

Joe isn't in the book; I think he's just sort of the classic salty noir hero, the haggard detective. Frank and I expanded on that and tried to make him as specific as we possibly could. I think what's cool about the series is, you really don't know anything about Joe Teague, even after the pilot. He does what he does. You don't know why he's doing it. I think that's a really cool thing. You don't get that on TV much. It's asking a lot of the audience. But if the audience invests, and if the audience sticks around through the season, all those questions will be answered. It reveals it as a very slow burn, as film noir is supposed to. The world will just get bigger, and bigger, and bigger, as more characters are introduced, the same way "Walking Dead" started off, as this narrow character study of Rick Grimes, and then it grew. "Mob City" is such a wonderful, colorful world that Frank is going to introduce.

Did Frank create Joe for you?

Frank said he was writing this thing for me. I went right on to doing a movie after "The Walking Dead," and he sent me the script. I think one of the first descriptions [of Joe] read, "Joe Teague is equal parts handsome and brutal, with a boxer's nose." I said, "Yeah, you wrote it for me. You got the messed-up nose" (laughing). That was it.

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

What kind of preparation did you do then to play this role? What kind of discussions did you have with Frank about Joe? As you said, he's a classic noir character, but it's very clear there's a lot more to him.

That's the thing. Look, I really needed to get educated in noir, because I knew nothing about the genre. I read a lot of Raymond Chandler and watched a ton of movies and listened to a lot of music. I have my own characters from movies that I definitely stole from, but the Dave Klein character from the "White Jazz" book is another one that was … that [James] Ellroy book really helped me a lot.

We're in this classic age of television now where we have these antiheroes on all these great shows, whether it's Don Draper or Walter White or Rick Grimes. We are told why they're going to do what they're going to do. Then, they start to do a bunch of bad sh--. We follow them. We believe in them, and for some reason, we root for them, even though they're doing this bad stuff, because we know why they're doing it. On this show, it's a little bit different. You're not going to know why Joe Teague is doing what he's doing. It will reveal itself. But like film noir, he's going to keep all of his reasons close to the vest. Everything's going to be shrouded in secrecy and mystery. Interestingly, as the problem gets bigger, we get more and more clues to why Joe is doing what he's doing. The story will start really bleeding into the real factual history of Los Angeles. Many mysteries in the history of L.A. will be answered by these fictional characters and by these fictional circumstances, which I think is just so cool.

Get to know Joe:

There are hints that the story will intersect with Hollywood history…

Yeah, especially with the Mob. I don't want to give away too much, but this whole thing starts with a number in a matchbook that Joe finds in his mailbox. Mundane things, the kind of things that happen to cops all the time. But it will start to really affect him personally. It will just grow, and spiral, and get bigger, more dangerous, and more brutal. As it grows, it starts to involve real historical figures from L.A. Frank uses that device to take this fictional problem, this little, teeny, mundane, focused problem, and as it grows, it will start affecting the entire city of Los Angeles. That's when he starts bringing in the real history, the historic facts. It's all about mystery. It's all about not knowing, and finding out is going to be, in my opinion, the fun of the series. I hope people stick around for it.

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The series is so authentic, such a detailed look at that time period. It must have been fun to immerse yourself in that world.

Oh, it was. Frank [is] a guy that's all about quality. He is not trying to sell soap. He is not trying to please people. He's trying to honor his heart and the storytelling. He's one of the best. Look what he did with "The Walking Dead" — he took the horror genre, a genre that he loved, the zombie genre, and said, "Let's put this on TV, but do some kick ass storytelling, create some great characters, and stretch it out over time, introduce the real classic horror genre to the American TV audience." It's the same thing he's doing with noir. It's a genre he loves, he cares about. He's not trying to … this is not "Gangster Squad." Nothing against that movie, but ["Mob City"] is not the modern take on noir, where people are speaking like they speak today. It's shot like classic noir. [The dialogue] is classic noir. A lot of the acting style is classic noir style. That was definitely the point.

You mentioned "The Walking Dead" ... are you still a viewer?

Yeah, absolutely. The cast of that show and the crew of that show are my family and always will be. We still keep in very close contact. I'll always be a fan. It's actually more fun being a fan, because I don't know what's going to happen (laughing). I dig watching it. I'm doing a movie in England now, so I get to see my friend Andy Lincoln very soon. I'm really looking forward to that.

Do you ask for spoilers?

No. When I see Norman [Reedus], when I talk to Norman and Andy, I just say, "Before we start talking, I don't want to hear a damn thing." They follow the rules. They know not to mess with me about that!

Watch a preview of the next episode of "Mob City":

"Mob City" continues Dec. 11 and 18 at 9 p.m. on TNT.