The course of true love rarely runs untrammeled in Adam Rapp’s increasingly overpopulated world — he has written more than a dozen plays, books, and films since 2001, notably last year’s toxic love triangle “Red Light Winter.” But the courtship at the center of his ostentatiously bizarre “Essential Self-Defense” seems particularly questionable.

It doesn’t exactly qualify as a “meet-cute” when Sadie Day (Heather Goldenhersh) returns to Yul Carroll (Rapp regular Paul Sparks) the tooth she knocked out of his head. They have a history of sorts: Yul, who spins conspiracy theories in a wheedling, traumatized monotone, has been reduced to working as a well-padded “assailant” at the self-defense class Sadie attends.

Still, this orthodontic rendezvous is the first time the repressed Sadie gets to break the ice with conversation.

Read any good books lately, Yul? Actually, Yul would prefer that you not finish sentences with his name: “It’s what the drones in human resources do when they begin the termination process.”

So, Yul, read any good books lately? As it happens, Yul is currently reading “375,413 Ways To Make a Bomb,” and his sole bit of dinner-party commentary in reference to “Mein Kampf” is, “That guy really struggled.”

Hmmmm. Yul, when’s your birthday? “Why, are you involved with some sort of database? … That kind of information makes me feel like I have scabs all over my body.”

It is around this point that women typically hand over the tooth and turn their attentions elsewhere. Not Sadie, an editor for children’s books who is governed by her own anxieties just as firmly as Yul is by his paranoid ramblings. But as children begin disappearing en masse from this small Midwestern town and the populace aims its suspicions at Yul, will Sadie’s fixation on a predatory menace lurking outside her home prove prophetic?

“Essential Self-Defense,” directed with a relative minimum of fuss by Carolyn Cantor, has the misfortune of opening on the heels of Bob Glaudini’s more contained and less cloying “Jack Goes Boating,” another story of misfits falling in vaguely ominous love. It even features its own set by the gifted “Boating” designer, David Korins, who once again surrounds an unassuming living space with an open expanse that morphs into a half-dozen other urban locales. (“Essential” is being presented by the visually adventurous Edge Theater, which was cofounded by Mr. Korins and Ms. Cantor, as well as by Playwrights Horizons.)

But while the title character in the latter play derives solace from a tinny reggae song, the inhabitants of Mr. Rapp’s work find transcendence a bit farther afield. Sadie achieves it through beating the stuffing out of a (mostly) padded guy. Yul achieves it through civil disobedience and blistering garage rock at an alloriginals (!) karaoke bar. Others achieve it through vigilante violence and adolescent hooliganism. (Ms. Cantor’s capable supporting cast includes Guy Boyd as a jovial barber and Michael Chernus as a raucous Russian émigré.) And perhaps one of these characters is achieving it through killing small children. Or perhaps not: The kid-snatching angle, despite a portentous early buildup, frequently feels like a MacGuffin.

And what about Mr. Rapp himself? It’s not too outlandish to suggest that the author — who hit the ground running with “Nocturne” when he was barely 30 and who has generally favored a dystopian blend of hyperrealism and linguistic virtuosity since then — is seeking a little release of his own.

Mr. Rapp seems to be reaching back to the anarchic, undisciplined earlier pieces he never got (or never chose) to write. When you’ve distilled the minute-to-minute sufferings of a diaper-wearing Desert Storm veteran on Christmas Eve (“Blackbird”) or the torpor of a strung-out rock band, complete with onstage urination (“Finer Noble Gases”), why not chuck it all into the air and go with a roller-disco dream sequence instead?

Mr. Sparks’s hangdog menace and strangely parsed line readings have enlivened many works by Mr. Rapp and other young writers. But Yul’s maladjusted monotone, while appropriate, deprives Mr. Sparks of his more alluring qualities. Ms. Goldenhersh, meanwhile, draws the evening’s most difficult assignment, making both Sadie’s attention to Yul and her own paralyzing neuroses plausible without succumbing to preciosity. Ms. Cantor, who can’t always save the author from his more baroque excesses, does her strongest work here in making sense of this fairly ludicrous character.

The first hint of Sadie’s wilder side comes when she invites Yul to that rock ‘n’ roll karaoke bar, where Mr. Rapp introduces a guitar-and-drums duo (Lucas Papaelias and Ray Rizzo) whose eclectic stylings punctuate much of the play. It’s Wingin’ It Wednesday at the bar, and the karaoke performances range from a deathmetal dirge sung by the menacing Klieg the Butcher (“Klieg the Butcher’s Right Hand Is the Strongest Appendage in the World” is the beginning of its title) to a roof-blasting bit of garage punk from the heretofore meek Yul.

Mr. Rapp collaborated with the two musicians on the music and lyrics for the extensive karaoke sequences, and attempting to parse his unaccountably sprawling efforts here and throughout “Essential Self-Defense” is akin to watching a moody troubadour such as Leonard Cohen turn into a 1970s prog-rock combo. Those who prefer Adam Rapp unplugged and on target would be advised to tune out this time. With two more plays and a film adaptation of “Blackbird” still to come in 2007, you shouldn’t have to wait long.

Until April 15 (416 W. 42nd St., between Ninth and Tenth avenues, 212-279-4200).