Being made to feel uncomfortable or even repulsed by the behavior of men comes as no surprise in a Neil LaBute play, but being moved by his male characters is more unexpected.

Being made to feel uncomfortable or even repulsed by the behavior of men comes as no surprise in a Neil LaBute play, but being moved by his male characters is more unexpected. In “Fat Pig,” the writer’s ability to make his audience empathize with the protagonist’s crippling cowardice yielded uncharacteristic emotional rewards. In “Reasons to Be Pretty,” which completes a trilogy of four-character plays about the unhealthy obsession with physical beauty that began with “The Shape of Things,” the playwright once again softens his tendency toward cold, clinical assessment with a warming dose of compassion. The result is both absorbing and affecting.

This is a thoughtful, mature play without the sour superiority or shocking twists and dark revelations that have become formulaic in LaBute’s work.

Often the writer’s provocations have been channeled through men who were proudly unrepentant about their ruthlessness, misogyny and immorality. But the protagonist here not only acknowledges his weaknesses, they cause him shame and suffering. “Fat Pig” afforded a glimpse into the bruised soul of a man whose stupidity cost him a chance at happiness. That insight cuts even deeper here with bookish warehouse worker Greg, played with acute self-exposure by Thomas Sadoski. Perhaps more than any other male character LaBute has created, Greg takes responsibility for his failings.

The play opens with the conflict already at boiling point as enraged Steph (Alison Pill) confronts Greg, her partner of four years, about a perceived slight. Though we never learn exactly what he said, it emerges that while concurring with his night-shift buddy Kent (Pablo Schreiber) on the attractiveness of a new girl in shipping, Greg made an unfavorable comparison to Steph. A security guard at the same firm, Kent’s wife Carly (Piper Perabo), reported the conversation back to Steph, who promptly exits the relationship, rebuffing Greg’s repeated attempts to make it up to her.

Further complications surface when Kent begins an affair with the unseen new colleague. He confides in Greg about his sexual exploits, but Greg is too busy contemplating the causes of his loneliness to listen, and too intimidated by his bullying friend to voice his discomfort about being a party to marital infidelity.

When pregnant Carly airs her suspicions about her husband to Greg, he at first tries to stay neutral, then gets trapped by the rules of male loyalty into lying to corroborate Kent’s alibi. But when Greg refuses to continue covering for Kent, friction between the two guys deepens, causing the differences between them to become irreconcilable.

Director Terry Kinney keeps the confrontations tense, volatile and mostly unpredictable — whether it’s the awkwardness of long-term male friends with nothing in common beyond their history or the timid mutual explorations of former lovers, negotiating unhealed wounds while gently testing the depths of residual affections. The bristling scenes between Steph and Greg are especially strong, from their first raw screaming match to her bilious public humiliation of him by reading a list of his physical flaws; from their distant but rueful unplanned meeting to Steph’s final, painfully shy attempt to ascertain if there’s any way to salvage their relationship.

With her high, intelligent forehead and intense eyes, it’s easy to buy Pill as a woman whose fragile self-esteem is ruled by her perception of herself as odd-looking rather than attractive. This feeds into LaBute’s view of beauty as being entirely subjective, with the conventional standard for prettiness creating a tyranny for woman on both sides of the appearance divide. Even Perabo’s cute, tidily packaged Carly addresses in a monologue the ways in which being easy on the eyes has worked against her, from dismissal of her nonphysical attributes to undue attention from creeps.

Each of the four characters opens up in a monologue, and while Greg, in the final one, gets to articulate fully the themes of the play and his own emotional maturity through experience, the device does feel a little schematic. With LaBute’s writing so sharp and his dialogue so spiky in the interplay between the characters, one wishes he could have found ways to integrate his concerns more seamlessly into the dramatic fabric, without resorting to direct address.

Nevertheless, there’s an insightfulness and texture to the observations here that’s always compelling. This is perhaps amplified by the shift away from the sleek corporate or professional worlds LaBute’s plays often inhabit into a blue-collar milieu in which the characters’ lives are punctuated by time clocks and pay dates. David Gallo’s versatile set, backed by a container cage of warehouse goods, and Sarah J. Holden’s unfussy costumes help cement that grounding among real people.

Perabo’s stage inexperience sometimes shows, and following her work in “The Lieutenant of Inishmore,” “Blackbird” and “Mauritius,” the talented Pill needs to be careful that her fiery explosions don’t turn into mannerisms. But all four actors etch recognizable, multidimensional characters and never try to whitewash their faults.

As he showed in “Awake and Sing!” and “Dying City,” Schreiber has considerable range, bringing complexity to what could have been just another loathsome, LaButean archetype, his personal relationships irredeemably polluted by brutal male competitiveness. But the play’s emotional focus is Greg, a smart, decent, unassuming guy — hungry to better his situation yet too aware of his limitations to be pushy about it. The authenticity of naked feeling and self-reflection Sadoski brings to the role is instrumental in placing “Reasons to Be Pretty” among the prolific LaBute’s more satisfying plays.

Reasons to Be Pretty

Lucille Lortel Theater; 198 seats; $59 top

• Production:An MCC Theater presentation, by special arrangement with the Lucille Lortel Foundation, of a play in two acts by Neil LaBute. Directed by Terry Kinney.
• Crew:Sets, David Gallo; costumes, Sarah J. Holden; lighting, David Weiner; original music and sound, Rob Milburn, Michael Bodeen; fight direction, Manny Siverio; production stage manager, Christine Lemme. Opened June 2, 2008. Reviewed May 29. Running time: 2 HOURS, 15 MIN.
• Cast:Carly - Piper Perabo Steph - Alison Pill Greg - Thomas Sadoski Kent - Pablo Schreiber