– It would have been so easy for Matthew McConaughey and Woody Harrelson to evolve into an aging Bo and Luke Duke, leaning on their good looks, Southern drawls and reputations as party boys. Instead, they’ve become two of Hollywood’s most intriguing actors, culminating in their work in HBO’s intense “True Detective,” an eight-part series that debuts Sunday.

McConaughey plays Rust Cohle, a Louisiana investigator who doesn’t seem to have a friend in the world and vomits philosophic notions, especially when looking into a macabre 1995 murder with an undercurrent of the occult. Harrelson is his seemingly strait-laced partner, Martin Hart, a family man who can barely tolerate Cohle’s eccentric behavior.

It’s the kind of mismatch that could describe an endless string of big-screen comedies, the kind these actors might have played earlier in their careers. But both men are no longer interested in doing mindless romantic comedies where abs are more important than acting and everyone knows your name.

“There are other things I’ve done that maybe had a quicker shelf life,” dead-panned McConaughey, who’s on an incredible run that includes an Oscar-bait performance in “Dallas Buyers Club,” Martin Scorsese’s new film “The Wolf of Wall Street” and last spring’s indie drama “Mud,” which won an Independent Spirit Award for ensemble performance.

“These things I’m doing now are feeling really relevant, and they’re piquing some people’s interests, and they’re resonating.”

Old buddies, new challenges

The shoot, which took place over six months, included one day in which the actors tore through 29 pages of dialogue. By Hollywood standards, that’s like tackling two triathlons in a row.

“That was the biggest mountain of the heap I’ve ever had,” McConaughey said. “I remember the wine tasted really good that night.”

Doing challenging material means making adjustments. The story, framed in flashbacks over a two-decade span as the now-estranged detectives describe their old case to officers looking into a similarly bizarre crime, forced the two longtime friends to re-evaluate their working relationship, which includes playing brothers in the 1999 Ron Howard comedy, “Ed TV.”

“With this project, we didn’t use a lot of our normal kind of shorthand, the way we finish each other’s sentences,” Harrelson said. “Matthew is one of the most gregarious, awesome guys I know, but here he was fully in character, and very much of an island.”

McConaughey originally read for the role of Hart, but found himself drawn to the more elusive Cohle, whom we find in 2012 looking like the kind of guy who hangs out in the parking lot of a mini-mart.
“I understood objectively why they would be coming to me with the role of Hart, because it was probably closer to some of my past work,” he said. “But Cohle was the voice that I remember thinking, ‘I can’t wait to turn the page and hear what’s coming out of this guy’s mouth.’ It’s got fire on it every time.”

Harrelson, whose films “Out of the Furnace” and “The Hunger Games: Catching Fire” are currently in theaters, has nothing but praise for his buddy, even though he also fancied the role of Cohle.

“I can’t imagine anybody playing that part better,” he said. “It’s a much different role from what I’ve ever seen him play before, but I think he knocked it out of the park.”

‘It was a 450-page film’

One reason HBO was able to snare two red-hot actors was its track record. Harrelson got an Emmy nomination for his work in the 2012 HBO film “Game Change” and had nothing but praise for the network. McConaughey’s involvement is the latest evidence that the wall between film and TV is crumbling down.

“Some of the best drama going on has been on television,” he said. “It was a 450-page film, is what it was.”

Then there’s the fact that there’s no long-term commitment. “Detective” is set up as a contained story that will wrap up in eight episodes. If there are future seasons of the series, they will revolve around completely different cases — much like “American Horror Story.”

“There could be a season that’s much more of a widespread conspiracy thriller, a season that’s a small-town murder mystery, a season where nobody is murdered and it’s a master criminal versus a rogue detective or something,” said series creator Nic Pizzolatto, a former novelist who wrote all eight episodes. “I mean, theoretically you could tell Faulkner’s ‘Absalom Absalom!’ as a season of ‘True Detective’ because it’s told as a mystery story. As long as there is some crime in there.”

For now, though, the emphasis is on the actors, who will certainly be Emmy contenders later this year. McConaughey in particular could be reveling in the praise he’s gotten lately, but he’s not about to break away to take a victory lap.

“I haven’t really been looking in the rearview mirror for a while — and I hope I don’t,” he said.

Neal Justin • 612-673-7431