A mom (Judi Dench) and a reporter (Steve Coogan) search for her son in “Philomena.” (The Weinstein Company)

It’s probably normal to be nervous as you’re standing in a hotel suite, waiting for Steve Coogan to walk through the door. After all, he’s famous for playing jerks — narcissistic radio/TV personality Alan Partridge and the guy named “Steve Coogan” in 2010’s “The Trip” come to mind — and playing them unnervingly well. Instead, what you get is someone a little quieter, a little softer (and, OK, a little shorter) than what you expected. And “Philomena,” which opens locally Wednesday, is not the movie you’d expect Jerk Steve Coogan to write, much less star in.

“I wanted to do something different,” the British actor says. “In the U.K. I’m kind of typecast in very broad comedy and I enjoy that, but it’s very hard to break out of that sometimes.” While he was in New York filming 2010’s “The Other Guys” (in which he plays a jerk), he saw his way out.

“I was looking at the Guardian newspaper online,” he says, “and I read this article about this Irish woman looking for her son and I found it really moving, and I thought straightaway, ‘There’s a movie in this.’ ”

He immediately bought the rights to the story (the book “The Lost Child of Philomena Lee” came out in 2009) and enlisted the help of co-screenwriter Jeff Pope. (“He knows about writing drama, and I don’t,” Coogan, 48, says.) Eventually Stephen Frears (“The Queen”) signed on to direct.

The film is based on the true story of Philomena Lee (played by Judi Dench), who in 1952 gave birth to a son out of wedlock, and British journalist Martin Sixsmith (Coogan). Lee was one of the estimated 30,000 so-called Magdalene Sister slaves, unmarried Irish mothers who toiled in near-slavery in Catholic laundries. (The final laundry in Ireland closed in 1996.) Three years into Lee’s forced four-year stay (to reimburse the nuns for her medical expenses and room and board), her son was sold to an American couple.

In the film, Philomena’s daughter discovers her mom’s secret and reaches out to Martin to tell the story. He’s been recently fired from his job as a political journalist over a hinted-at scandal and takes the assignment, even though he feels such a human-interest story is beneath him. The two embark on an odd-couple road trip in search of her now-grown son, going from Ireland to the U.S. (including D.C. and its suburbs) and back again.

Coogan wrote the character of Martin with plenty of safe space to work in. “Martin is half based on the real Martin and partly my own stuff, my own points of view,” he says. “I started from the premise that some people who are cynical don’t really want to be cynical, but think that’s the best way to go about things: People should be cynical because they’re smart, if they’re not cynical that means they’re stupid.”

It’s a belief Coogan hoped to combat with the film: “I wanted [Martin] to be someone who would watch this kind of film and think, ‘Oh, it’s all bulls— about an old Irish lady.’ ” Eventually, though, Martin (and the audience) discovers that there’s steel holding up that Irish rose.

Coogan’s fans will still find the acerbic humor he’s known for, but here he uses it in small, pointed doses that keep “Philomena” from veering too close to Movie of the Week territory. “Whenever we came up against a moment that could have been schmaltzy, we were very careful to use humor to undercut it and stop it being too self-important,” he says.

So it may be that “Philomena” — full of sweetness but cut with acidity — is the most Steve Coogan-esque film that Steve Coogan has done. After all, you were worried he was a jerk and then he offers you coffee from his suite’s snack cart (and then tea … and then water) as soon as you shake hands, and you realize that maybe you should stop being so quick to judge.

Coogan’s Characters

‘24 Hour Party People’
Steve Coogan plays Factory Records owner Tony Wilson, who gave the bands Joy Division and Happy Mondays their big break. He also breaks the fourth wall throughout the 2002 comedy.

‘The Trip’
Equally funny and depressing, this 2010 film follows Coogan and Rob Brydon (playing versions of themselves) as they travel England eating food and doing impressions of Michael Caine and Sean Connery.

Alan Partridge
Co-created by “Veep” mastermind Armando Iannucci, Coogan’s signature character — a self-obsessed radio and TV host — has appeared in several TV series and a 2013 feature film.