Iowa native Michelle Monaghan discusses growing up Midwestern and her time on the hit HBO show, 'True Detective'. (Posted March 5, 2014)

In one of the most poignant scenes in HBO’s “True Detective,” Michelle Monaghan’s Maggie Hart accuses her husband, Martin, played by Woody Harrelson, of being a promiscuous “sulky teenager.”

“You put a ceiling on your life, on everything, because you won’t change,” she says, exasperated.

It’s a pivotal scene that marks the first time viewers see just how disillusioned Maggie is with her marriage, and Monaghan shines in it, portraying strength, vulnerability, sadness and hope from one quotable line to the next.

“I was moved by that (scene),” Monaghan recalled during a recent phone interview from her LA home. “I think all of the people who saw it were too. ... It’s confronting for a lot of people because it’s really honest and very real. It’s how people speak and that’s powerful.”

Unlike her fictional husband, Monaghan has never put a ceiling on her life. Growing up in Winthrop, Iowa — a town of 850 people according to 2010 Census Bureau data — she said Hollywood seemed so separate from her life. But merely 14 years after starting her acting career, Monaghan, 37, has not only shared the screen but held her own with stars such as Tom Cruise (“Mission: Impossible III”), Jake Gyllenhaal (“Source Code”), Robert Downey Jr. (“Kiss Kiss Bang Bang”) and her “True Detective” co-stars Harrelson and Matthew McConaughey, who plays Martin’s partner, Rustin “Rust” Cohle.

“True Detective,” which with 2.3 million viewers had HBO’s biggest series premiere, follows Louisiana homicide detectives Hart and Cohle and spans 17 years. In 1995, the pair investigate the disturbing murder of a young woman and the crime’s possible occult connections. In 2012, the partners are questioned about their casework after a murder similar to the ’95 killing takes place and, in the most recent episode, they reunite to seemingly finish what they started.

The finale of the first season, a planned anthology series, will air Sunday, hopefully putting to rest speculation as to who is “The Yellow King,” the supposed cult leader and possible serial murderer. Whodunit theories surrounding the king’s identity have set the Internet abuzz for weeks.

The procedural aspect of “True Detective” is interesting and complex, but the heart of this show, its sweet, sticky nougat center, is the characters’ rich relationships and their tangled emotional webs.

“What’s really happening (in the show) is this incredible dissection of relationships and how they intersect and they converge and they change over time,” Monaghan said. “I think that is what is really grabbing people emotionally and at times even making it uncomfortable.”

Monaghan speaks with a laid-back cadence and a convivial tone that sounds as if she could erupt into a giggle at any moment. When asked if she had a specific personality within her school’s drama group — The comedian? The drama queen? — she laughs. “No, you have to remember I graduated with a class of 35 people,” she said. “We had basically just enough people to actually have a play.”

At East Buchanan High School, Monaghan was on student council, participated in the speech team and acted in the school’s plays. She was a typical small-town teenager, said her coach and director Cheryl Beatty, always respectful, kind and hardworking, especially when it came to the arts.

“She was always really good at figuring out what the script was demanding as far as the character she was playing,” Beatty said. “She had a knack for getting that character down exactly how you would expect them to be while throwing her own little personal flair into it.”

Monaghan started modeling in high school to earn money for college and spent the summer before her senior year working in Japan. After a semester at Iowa State University, she moved to Chicago to study journalism at Columbia College Chicago. Newscasting had long been an interest, she said.

“We were always talking about current events around the supper table,” she said. “I was just fascinated with how everyone else in the world lived, and I was interested in telling their story.

“I don’t really think now, having found my career as an actor, it’s that much of a departure,” she continued. “I’m still really fascinated with characters and people and telling their stories.”

In 1999, Monaghan moved to New York, where she studied with Alan Langdon at Circle in the Square Theatre School. Langdon remembered Monaghan as an excellent student, someone who “took in everything and processed it almost immediately.”

“She not only embraces the character but is also present as herself,” Langdon said. “There is some facet of herself that she’s able to reveal in the work that she’s doing, and I think that’s extraordinary. When I first saw her in ‘Mission: Impossible,’ for example, I thought my God, she is so connected, so alive, so expressive, so beautiful.”

Monaghan hasn’t been a TV show regular since her powerful turn as naive, well-meaning teacher Kimberly Woods on “Boston Public” in 2002. Woods stirred up racial tension at Winslow High School after hosting a discussion about affirmative action and eventually had to transfer when a student became obsessed with her.

It was the quality of “True Detective” that lured Monaghan back to the small screen, she said.

“It wasn’t necessarily about making a conscious decision to come back to TV,” she said. “It was really the level of material and the caliber of people involved that decided it for me. Had it been a film, I would have made the same decision.”