Deeply obsessive love stories aren't rendered as comedies particularly often—they're more likely to show up as taut films with titillating titles like Fatal Attraction and Basic Instinct. But when you think about it, single-mindedness of focus, taken to absurd extremes, is a crucial component of farce, and isn't that a perfect word for describing many romantic relationships? So come up with two killer characters who really want each other and something or someone to get in their way and add an equal amount of laughs, and you have the makings of a crackling dramatic work. That's the recipe A.D. Penedo has followed for his play at Manhattan Theatre Source as part of the New York International Fringe Festival, The Three Times She Knocked, and the results are tasty indeed.

It helps that, in Bob D'Haene and Isabel Richardson, Penedo and director Christopher Windom have found an electric pair to occupy the story's center. Both actors are quick of tongue, even speedier of wit, and magnetic enough to convince you that proto lovers Eric and Tara are hot enough for each other to ruin their lives, as well as those of their spouses. (The statuesque, deceptively demure Richardson has especially little trouble convincing you Tara is a home-wrecker waiting to happen.) And because Penedo has underwritten so many of his scenes—something that is only occasionally a liability—you get to know these two just as gradually and just as well as they come to know each other over three separate scenes. (In this way, Penedo also invokes David Mamet's Oleanna.)

Each encounter begins, as the title suggests, with a knock on the door of Eric's office, which highlights that Eric and Tara are fraught by more than just their marital status. Though both work at the same firm, he holds a powerful position in accounting and she is a junior associate in a different department. It would be inappropriate for them to mingle, Eric insists—he even refuses to allow Tara to shut the door when she first enters his office, ostensibly to test out his new ergonomic chair. He also had a slight problem in the past, he reveals: Oh, it was 11 years ago that he contemplated cheating on his wife with a feisty Midwesterner named Steph who had a unique way of chewing gum, but he's never recovered from either the feelings he felt for her or the way their fling ended.

But a strange thing happens as Eric reveals increasingly intimate details about himself: Tara becomes increasingly interested in him. Though they make an effort to stop seeing each other—the visits we see are each several weeks apart—they're always drawn back together for another verbal go-around. And whenever they reconnect, Penedo ups the stakes and the tension until you're every bit as anxious as they are to see whether they'll manage to solve their mutual problems. So smooth are the transitions, and so gentle does the emotional illumination come, that by the harrowing final scene, in which both learn the ultimate price of their admissions and betrayals, you really can't see the final turns of plot coming.

That finale skirts a bit too closely with narrative overkill, in defiance of the subtleties that fuel the rest of the action. It also reveals the chief problem with the play: Penedo dwells so much on Eric and his personal histories that Tara's eventual opening up almost feels like an afterthought; the two are not remotely on equal footing in terms of the dialogue. This helps Tara somewhat, in that it forces her to seem more like the intangible object of desire Eric perceives, but she still comes across as more vague than is perhaps ideal for the first two-thirds of the play.

Richardson's luscious way with a sentence makes the most of her every line, however, and she catalogs the full span of Tara's conflictions just within the minute changes of arch in her eyebrows. And D'Haene skillfully negotiates the blending of Eric's libido and propriety into a man who reads exactly as he should: as someone who is always just on the verge of losing control. The question of whether he'll go over the edge entirely, and what the ramifications of such an act would be, is the most intoxicating question in The Three Times She Knocked. But Penedo, Windom, and their actors always leave you convinced that, whatever happens, you are in strong, capable, and devious hands

The Three Times She Knocked
Tickets, Venue, and Current Performance Schedule: www.fringenyc.org