Anyone who goes to Amsterdam’s red-light district with the guy who stole his girlfriend – and then stays cooped up in his ratty room with a Latin-English dictionary – has his work cut out for him as a romantic hero. But Adam Rapp has created one in Matt, the brooding young playwright at the center of his wickedly funny and occasionally quite sad “Red Light Winter.”

In the past, Mr. Rapp, the reigning laureate of articulate squalor, has featured such onstage treats as urination and the changing of adult diapers. Here he focuses on a more universal set of indignities: those that come with unrequited love. Even when he trips himself up on the over caffeinated chatter – a common fate when an author directs his own work – Mr. Rapp’s clear-eyed empathy results in a romance that’s fairly touching, in a dingy sort of way. It’s the kind of story that the perpetually “emerging” playwright Matt (Christopher Denham) would love to be able to tell.

Matt and his old college chum Davis (Gary Wilmes) have arrived in the Netherlands for what Davis calls “Amsterdamage” – i.e., drugs and sex. Matt actually lays off the former: He is on antibiotics after a bout of gastrointestinal mayhem that Mr. Rapp describes in considerable detail, including the memorable phrase “violent verdant volume.” The sex comes courtesy of the French-speaking hooker Christina (Lisa Joyce), who accompanies Davis back to the guys’ hostel room.

What passes for foreplay as far as Davis and Matt are concerned is a relentless barrage of intellectual one-upmanship with more than a tinge of homoerotic longing. Christina shows no indication of understanding much English, so this new round of violent verdant volume between the two men – laced with “Aristotelian” and “methinks” and “impending mega-tonnage” – is clearly intended for each other.

The simulated coupling that ensues once Davis leaves has generated a fair amount of heavy-breathing press, but the nudity is less extensive than what was on display during another recent Barrow Street Theatre inhabitant, “Bug.” More to the point here is the afterglow: The blink-and-you-miss-it sex hardly seems memorable, but the experience lodges deep in the memory of at least one participant. As a result of the goings-on in Amsterdam (including an off-stage romp between Davis and Christina), two of these three characters will fall rhapsodically, helplessly in love – but not with each other.

Deep within Mr. Rapp’s thickets of verbiage, is a simple, old-fashioned love triangle that gets untangled the following winter in New York City. Through a series of circumstances that test the limits of the author’s storytelling skills, Act II finds all three characters in Matt’s squalid East Village apartment. (Todd Rosenthal’s letter-perfect set, with its groaning bookshelves and loose floor tiles, follows the example of Mr. Rapp’s “Blackbird” and “Finer Noble Gases” in impressing the audience and making them itch at the same time.)

Matt is struggling to write a play about his Amsterdam experiences – the meta-fiction trickery gets a little too smirky here – and he cuts to the core of the genre when he says, “My instincts are to let it sort of fade out, to like resist the big cliched, melodramatic ending, but I keep writing into this like weird corner of confrontation and emotional apocalypse.”

Love triangles are so compelling precisely because even those weird corners are inherently cliched. Three lines can only converge or diverge so many ways; the only real questions are whether the characters will get around to ‘fessing up and, more important, with how much success. Those familiar with Mr. Rapp’s work – his first play, “Nocturne,” told the story of a man who accidentally decapitates his 9-year-old sister – can make a reasonably good guess at the answer to this final question.

Matt’s apartment is stuffed with paperbacks by canonized brooders like Frederick Exley, John Fante, Anton Chekhov, and not Raymond Carver; in fact, a large photo of Carver has been defaced on the wall. While in Amsterdam, Davis goads Matt into a vehement defense of Henry Miller at Carver’s expense: “The biggest difference between Carver and Miller, besides Carver’s obvious lack of style passing off as minimalism, is that Carver was a writer and Miller was an author.”

The irony here is that Mr. Rapp’s sexual politics would be far more familiar to Carver than to Miller. Nearly every sexual encounter seen or described in “Red Light Winter” involves a remarkable amount of falsity. One or both of the partners conceal crucial pieces of information that have major ramifications. This fraught, self-denying spirit, so common in Carver and his anatomized-angst peers, is antithetical to the rutting truth-tellers of Miller at his most pungent.

The character of Davis, however, would more likely be found in the works of Martin Amis on a particularly dyspeptic day, or maybe the Marquis de Sade. Mr. Rapp’s glee in writing material for this rotter is fairly contagious, as his caddishness displays itself in ways both typical (ego-deflating comments, casual racism) and baroque (sticking Matt’s dish towel down his pants and then putting it back). Davis may never get the emotional shadings of the other two characters, but Mr. Wilmes provides all the razor-sharp malevolence an author or audience could ever want. It may be a while before you look at a car seat the same way.

The lanky, scruffy Mr. Denham joins Paul Sparks and Dallas Roberts as actors with a natural flair for pulling off Mr. Rapp’s florid, almost painterly language. Best of all is the captivating Ms. Joyce, who makes a staggeringly assured New York debut as a woman capable of wounding and of being wounded. Most playwrights would move heaven and earth to give Christina a happy ending.

Adam Rapp is not most playwrights, and his pessimistic machinations occasionally feel as stage-managed as the joyous clinches at the end of a Hollywood romance. But his incisive blend of cruelty and confession may make “Red Light Winter” the most resonant (and commercially viable) work yet from a tough, tender, abundantly gifted young playwright.

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