"How do two friends that have always been partners and suddenly, one's a boss and one's not - how do we continue that relationship?" pitches Eric McCormack as to the heart of his new TNT series "Trust Me," premiering tonight at 10:00/9:00c on TNT. Set at the fictional Rothman Greene & Mohr agency in Chicago, the series tracks Mason McGuire (McCormack), an art director who's just been promoted to creative director over his longtime partner, Conner (Tom Cavanagh). I had the chance to sit down with both McCormack and Cavanagh, as well as the show's creators, during a set visit last month.

So why another series set in the world of advertising? "[John Coveny and I] both spent 10 plus years working in advertising in Chicago," explains co-creator Hunt Baldwin. "And they always tell you to write what you know." Coveny adds, "We want to tell what happens behind the scenes - the pain and the agony and the joy of coming up with a print ad, a TV commercial - and show people how that happens."

Baldwin notes that the perception of the advertising world is that it's "lying liars telling lies and selling things to people who don't need them... but that's not what it's like, it's not our experience with it. We have a lot of affection for that world and the people that do it."

So what about the characters, whom Coveny and Baldwin note are loosely based on themselves. "I'm the mercurial one if you want to use that word," Cavanagh says about his singularly-named Conner, while McCormack notes his character, Mason, is "sort of the attention-to-details [type] which is why I get the promotion."

McCormack says they aren't easy to stereotype though. "What I love is [about the show] is that they write to the envy - I envy that he's still single, I envy that our old boss worshiped him..." Cavanagh interrupts, "And I want to doink his wife, [Conner] wants to doink his wife."

The guys' chemistry ("He's carbon based, " Cavanagh quips.) is also something they're both proud of. "I think we both sensed it would be good without even knowing each other," McCormack reveals. "And sure enough, we got in the room and there was a kind of caffeinated ba-bing, ba-bing, ba-bing and that's not only happened in the moment but it also affected how they write the show and how they approached it." He later notes that the producers "retooled the pilot a little bit based on that. The original pilot, we're not even in the same room until the second act. And they showed it to so focus groups and they were like, 'We like when these two guys talked to each other. It's funny and fast, can we get them together [sooner]?'"

McCormack and Cavanagh also aren't shy about "Trust Me's" obvious comparisons to AMC's "Mad Men." "We really lobbied hard for 'Madder Men,'" Cavanagh jokes about the show's title, which was originally "Truth in Advertising." McCormack is quick to point out that "if 'Mad Men's' sort of the beginning of the golden age of advertising, this show is kind of about the end of it - having to deal with TiVo and the internet, the 18-year-olds finding new, genius ways to get the word out and we're still working on the old ways. We were taught by those guys probably. Don Draper would be how old now? Well he'd be 70. He taught people that taught us the ways and the ways are dying out. We're constantly having to deal with the fact we're not keeping up with the Joneses."

And what about McCormack's transition to both drama and cable: "It's a weird time because, unlike say a sitcom on network television where you're three episodes in and you're airing, we're pretty much going to finish all 12 [plus the pilot] by the time this thing airs, or almost. I'm kind of anxious for this thing to be on the air. I want people to see it. I think it's really good and I'm excited that TNT's gonna make people know about it."

The real marvel for the guys however is the unexpected. "The day to day on this show, six episodes in - we've already lost our biggest account, there's serious jeopardy every time about losing our jobs," says McCormack. And that's not all: "We're at each other's throats, there's romance, intrigue and deceit! It's a whirlwind of fascination!" Cavanagh smiles.

Catch the chemistry, jeopardy, romance and intrigue of "Trust Me" tonight at 10:00/9:00c on TNT.