Pam and Dixon are having that experience many parents have when they look at their teenage son or daughter and think, "Who is this alien living in my home?"

Playwright Carly Mensch, a producer of the HBO series "Weeds," titled her family comedy "Oblivion" -- a title that functions in the sci-fi realm but works equally well when worlds collide unexpectedly inside a nicely gentrified Brooklyn home.

In the play's Pittsburgh debut at City Theatre, Type A Pam is a TV documentarian, and her husband, Dixon, a dropout lawyer who writes fiction and enjoys his weed. They consider themselves to be open-minded until they learn daughter Julie has been lying to them: Instead of going on a planned college visit, she's gone on a religious retreat with her friend Bernard. She's finding her way to God instead of Wesleyan, and that couldn't be further from her parent's expectations than if she'd hopped a spaceship to Mars.

It's enough to shake anyone's faith in the things they believed to be self-evident.

"Oblivion's" cast of four is made up of newcomers to City, among them Julia Warner, who plays high school junior Julie. Ms. Warner is a Point Park graduate now based in New York, and Lisa Velten Smith, who plays Pam, recently moved to Pittsburgh.

"My first read-through I instantly connected with Julie," Ms. Warner said of the alienated teen who had been seeking a clique to call her own. "I too, played basketball in middle school, but I was extremely shy and awkward and didn't have that many friends. It took me a while to find my niche, my group of friends. That's how I fell into theater. I was instantly drawn to Julie and I think her journey is something everybody goes through."

While Julie is finding herself, her parents are trying to maintain their liberal cool and figure out what to make of this unexpected turn of events -- think what the hippie parents on "Family Ties" must have gone through when they realized their oldest son espoused the values of an investment banker.

In her New York Times review of "Oblivion" at the Westchester County Playhouse, Anita Gates wrote that the play has "sitcom leanings." Quentin Mare, who plays Dixon, said, "It had me laughing out loud, which is something I don't do often when reading."

With the laughs, though, are the complexities of navigating parenthood and marriage when one person does the unexpected or disappoints the other. Family ties are tested, in particular the mother-daughter bond.

Ms. Smith was reminded of something that "Quentin mentioned early on in the process: Pam really speaks to Julie as if we are equals ... and I believe there is something with mother and daughter, 'You will follow down this path because this is the best path for you.' And so it really is tense and very scary for Pam when she finds out what Julie is into. That's when it becomes earth-shattering and her belief is shaken."

Dixon also has taken an unexpected path in life, one that Mr. Mare can relate to "entirely."

"I used to work in the bond market, and I, like him, left a 'legitimate' profession where there was lots of money to go pursue, and I got into acting," the actor said.

Christopher Larkin's Bernard at first is unaware he has abetted Julie in deceiving her parents. He's on course to make a film with Julie that would please his idol, the film critic Pauline Kael.

"I never had that kind of idolatry growing up. I still don't have a single person or especially a filmmaker of any kind that I worship," Mr. Larkin said. "But I think Bernard's self-doubt, being his biggest self critic, is something I easily relate to. It probably started somewhere around junior year in high school and it's only gotten worse as time goes on. ..."

"Our little ray of sunshine," Mr. Mare teases his co-star, and everyone laughs. They are seated around a folding table in a City Theatre rehearsal room, well into the process of becoming a theater family under the guidance of Stuart Corden, a frequent director at City.

"I think the chemistry was there from the beginning," Ms. Warner said. "I was so excited to work with these people just from the first day."

"We all came in with open hearts and a willingness to trust each other," said Mr. Mare, with Ms. Smith adding, "I think that speaks a lot to Stuart. He picked an amazing team."

First Published: March 19, 2015, 4:00 a.m.