Harrison Bryan is not 15.

“I’ve been so blessed, since graduating, to be exclusively playing teenagers,” said the actor who portrays 15-year-old Christopher Boone in “The Curious Incident of the Dog in the Night-Time” at Round House Theatre. “But what’s so great about acting education is that they’re constantly working your play muscle, constantly getting you in touch with your inner child. Because of that, I don’t feel so removed from 19 years old.”

And that’s important, because “The Curious Incident of the Dog in the Night-Time,” Simon Stephens’ adaptation of Mark Haddon’s best-selling book, features a teenage protagonist. Christopher is a young man, possibly on the autism spectrum, who struggles with metaphors, celebrates math, has a tough time feeling empathy, and ultimately summons his courage and journeys to London to solve a mystery.

“When you’re doing any play, you want to tell a story,” said Tessa Klein, who plays Siobhan, one of Christopher’s teachers and his guide to emotion and communication. “Whether it’s a play that has no technical elements, or a play that has a lot of them — like this one.”

Pulling the technical elements and the story lines together in this Tony Award-winning show are co-directors Ryan Rilette and Jared Mezzocchi. Rilette is Round House’s artistic director, and Mezzocchi also serves as projections designer on the team that uses digitally enhanced staging to bring the story to life.

“Jared is as intuitive as he is technically savvy,” said Bryan. “He also was an actor. We’re as interested in experiencing moments of realism as we are in experiencing moments of heightened theatricality.”

The original Broadway production, Bryan pointed out, spent $6 million on its projections. As the play moves to regional theatres, he noted, more creative, cost-effective solutions are being found and applied.

“There are a lot of levels to this story,” said Klein. “We’ve taken what we’ve done as actors in the rehearsal rooms and added in this incredible projection and sound. I’m excited about how those things combine to tell this simple, heartwarming story in a visually stunning way.”

The story first surfaced in 2003, an award-winning mystery novel about a boy who sets out to clear himself when his neighbor’s poodle turns up dead. A tale of being different and overcoming fear, “The Curious Incident of the Dog in the Night-Time” was adapted into a play in London in 2013 and traveled from the West End to Broadway in 2014. Now it’s at Round House, where Klein and Bryan are making their D.C.-area debuts in a cast filled with Round House veterans.

“This play is about family and communication,” said Bryan, who has a bachelor of fine arts degree from Boston University as well as classical training at the London Academy of Music and Dramatic Art (LAMDA). “It is told through the lens of a human on the neuro-diverse spectrum, but at its core, it’s about how we communicate truth, and how our family can be our biggest support system.”

Which it is for the “Brooklyn, born and raised” actor, who is also a writer, a puppeteer and a professional clown. “I still live in the same house I grew up in,” he said. It was a house where theatre ruled.

“My father had not even seen a play until he met my mom,” Bryan explained. “But she was a double major in college — acting and English — and she introduced my sister and me to theatre at a very early age.” He reckons he saw his first Broadway show when he was about 4 years old; “introduced to the best of the best at a young age,” he recalled, adding that later on in life, “I was very lucky to study at BU, and then spend a semester in London studying Shakespeare — and what is now a passable British accent!”

He puts the accent to good use playing Christopher, who lives in Swindon, Wiltshire, but has to make his way to the big city, overcoming his fears. What’s Bryan afraid of? “One of my great fears is boredom,” he admitted. “I use my time as constructively and productively as possible, and part of that is playwriting and part of that is puppetry.

“It’s important that the future of American theatre isn’t just adaptations of movies,” he added. “So, the more new work I can add, the better.”

Klein, whose “new work” involves balancing parenting and performing, grew up in an artistic family, doing community theatre in Vermont, and earned a bachelor of fine arts degree in acting from Carnegie Mellon University. She relocated to the D.C. area with her family, and raved about Round House. “It’s very warm, very accommodating,” she said. “Which is not something you always find.”

Bryan agreed, saying he has wanted to work in the D.C. theatre community for some time, “because of the great things I’ve heard, and all of that has been proven true.

“I feel like I’ve been traded to an All-Star Team,” he added, noting that in “The Curious Incident of the Dog in the Night-Time” many of the supporting roles are small ones, albeit performed by a cast of D.C.’s finest actors. Ryan told Bryan he felt like he had “a bunch of Ferraris sitting in my garage,’” Bryan recalled. “What’s amazing is that because everyone is so incredibly capable, the amount of support I get is fantastic.”

And because it is “The Curious Incident of the Dog in the Night-Time,” the cast also features a golden retriever puppy. “He’s the best actor in the play,” deadpanned Klein. “A scene stealer!” agreed Bryan, who also shares scenes with a rat (played by three rodents in tandem) during his two-and-a-half hours onstage.

“There are very few plays like this,” he added, “in that it feels as epic and large as a musical. I think it will surpass people’s expectations of what a play can be.”

“The Curious Incident of the Dog in the Night-Time” runs through Dec. 22 at Round House Theatre, 4545 East-West Highway, Bethesda. Performances start at 7:30 p.m. Tuesdays, Wednesdays and Thursdays; 8 p.m. Fridays; 2 and 8 p.m. Saturdays and 2 p.m. Sundays. For tickets, ranging from $51 to $83, call 240-644-1100 or visit www.RoundHouseTheatre.org.