Bethany Anne Lind and Danny Gavigan in Signature Theatre's production of "Really Really." (Scott Suchman/Scott Suchman)

When Signature Theatre’s “Really Really” begins, it is early in the morning and it’s impossible to tell just what happened the night before.

It’s clear there was a party in the boys’ off-campus apartment, stage left, a classic kegger whose remains are the upturned Solo cups resting on the table and crushed Pabst Blue Ribbon cans scattered across the floor.

It’s clear that stage right is a girls’ apartment, inhabited by coeds who like to keep things tidy. They have curtained the windows, decluttered the coffee table, Lysoled the kitchen counters.

But that is where the clarity ends, because the plot of “Really Really” hinges on an allegation of a sexual nature that may or may not be true, because everyone involved has memories of that night that are foggy like a window after the rain, blurred by beer and sleep and, perhaps, a subconscious desire to forget.

Already the line between the girls’ pristine dwelling and the chaos just beside it is fading; by the end of Act 1 it will disappear, and no one’s life will be clean anymore.

Paul Downs Colaizzo. (Courtesy of Paradigm Agency)

“Really Really” was written by the 26-year-old Paul Downs Colaizzo. It promises to be an intense and intimate two hours. The show, intended for mature audiences, contains explicit situations and the kind of language this paper can’t print.

The crux of the play occurs “when a less privileged student accuses a member of the school’s rugby team of an act of sexual aggression,” explained Colaizzo.

“People are scared because it does deal with some tough issues,” said Eric Schaeffer, Signature’s artistic director. “That, to me, is what makes exciting theater.”

Colaizzo, who is literally on the edge of his seat when talking about the show, says cast member Kim Rosen’s description of the title is best: that it’s about the distinction between “what you want and what you really, really want.” A woman at a first look for Signature’s funders asked him whether audiences could expect to leave the theater “with hope.” Colaizzo said no.

“It doesn’t hold any punches,” Schaeffer said. “It’s real life.”

* * *

To put Colaizzo’s age in perspective, he is younger than the Apple Macintosh, younger than Mark Zuckerberg and younger than Zuckerberg’s big-screen embodiment, Jessie Eisenberg. He’s only a few years older than the writer wunderkind of the year, Tea Obreht, author of “The Tiger’s Wife.”

He is also the youngest playwright with whom Signature has ever worked, though Schaeffer said: “I don’t think of Paul as being inexperienced, because he’s come from an acting background, so he’s been on both sides of the footlights. He has a worldly sense about him.”

For Colaizzo “to have arrived at this point in his career so early, it really is very, very unusual and quite extraordinary,” said Richard Wesley, chair of the Goldberg Department of Dramatic Writing at New York University. (Colaizzo attended NYU but did not study under Wesley.)

Colaizzo’s achievement, Wesley said, is the equivalent of “a midshipman fresh out of the Naval Academy getting command of a destroyer. A junior executive just out of Wharton suddenly being given the keys to the executive suite at American Express. That’s what this kid has succeeded in doing: getting a play fully produced by a major theater company. It just doesn’t happen every day to 26-year-olds.”

Colaizzo committed to writing full time in 2009. Before that, he worked as an actor, participating in experimental theater at NYU (a sample of that experience, presented without context: “I was half-naked in war paint at P.S. 122 [a performance venue in the East Village] pretending to be a spider and ripping up underwear on a balcony.”) His first gig out of college was as a cast member of “Great Expectations” with TheatreworksUSA; he wrote the first draft of “Really Really” in the back seat of the 10-passenger van while on tour.

Since making the decision to focus on playwriting, Colaizzo hasn’t wasted any time: He was the associate writer for Broadway’s “Sister Act” last year, and a reading of his play “Pride in the Falls of Autrey Mill,” directed by David Schwimmer and starring Julie White and Jonathan Groff, took place in October.

Through the Kennedy Center’s Page to Stage program, Colaizzo held a reading of “Really Really” at the Kennedy Center in September 2009 — a reading he could not attend because, still working as an actor for bill-paying purposes, he was performing in the “High School Musical 2” tour.

Immediately after the reading, Matt Gardiner, who is directing the show at Signature, sent the script to Schaeffer.

“When I read the play, I just said, ‘This is so well-written,’ ” Schaeffer said. “I didn’t feel there were any untrue moments.”

Signature held a reading of the show before launching into a full production. At the end of the reading, Colaizzo remembered, “Eric said, ‘Everyone is afraid of this play, which is why we have to do it.’ ”

* * *

Maybe everyone has a reason to be afraid of this play. It occupies the intersection between violence and intimacy, perhaps the most terrifying crossroads imaginable. Which is exactly how the script describes the explicit scenes in the show, Gardiner said: It leaves out the specifics and includes only the adjectives, such as “terrifying.”

Gardiner, who is only one year older than Colaizzo, said that spending all this time in the heads of these characters is “doing a number on me and the way that I look at my own relationships. . . . This play is meant to and demands that this generation of people look at themselves and their actions. And so I find it very hard to separate these characters from my own reality.”

Blocking the scene of sexual aggression has been “emotionally draining. . . . [But] finding the physical language for the show is just as important for finding the actual words, [especially] for a show that’s so ambiguous. A lot of it is a mystery.”

Colaizzo’s plans after “Really Really” are also a mystery, at least until the name-brand organizations he’ll be working with give him the green light to spread the word. “Really Really” is the first play in Colaizzo’s “Want, Give, Get” trilogy, all of which focus on his generation. The other two works are “Little Gives,” written in 2009, which concerns faith and how young people deal with sacrificing to achieve desired ends, and “A Dog’s Tale (or The Thing About Getting),” written in 2010, about three friends who are linked by a traumatic childhood experience. Both have yet to be produced.

In the meantime, “Really Really” will get its world premiere at Signature through the end of March, possibly infuriating, scandalizing and offending audiences, though Colaizzo is prepared for any and all reactions.

“I’d say there are two kinds of theater: one you end with an answer, one you end with a question,” Colaizzo said. “This play does not give you the answer.”

Really Really

through March 25, Signature Theatre, 4200 Campbell Ave., Arlington. Call 703-820-9771 or visit