How many times can a playwright stress the appeal of flaws and errors before her audience grows a bit nervous?

This question comes up repeatedly in “Mauritius,” Theresa Rebeck’s intermittently diverting mash-up of con game and domestic drama. The labyrinthine plot hinges on the musty world of rare postage stamps, where mistakes (upside-down airplanes and the like) do indeed boost the value, and the inference is that Ms. Rebeck’s quintet of schemers similarly benefit from their imperfections.

But Ms. Rebeck, a prolific playwright making her Broadway debut, hammers this metaphor with a doggedness that draws unwelcome attention to her own plotting gaffes and ungainly speeches. In the process, she and director Doug Hughes squander a strong cast and allow the play’s twists and turns to spin a promising narrative into a series of credulity-straining confrontations.

Jackie (Allison Pill), a down-onher-luck young woman whose mother has just died, has inherited a potentially valuable stamp collection. She takes it to a philatelist shop run by the supercilious Philip (Dylan Baker), where an affable lug named Dennis (Bobby Cannavale) expresses interest both in the collection and in Jackie. Philip wants no part of the transactions, but Dennis is also friends with Sterling (F. Murray Abraham), a volatile stamp lover who prefers to do business with a suitcase full of cash. There’s a catch, though: The stamps technically belong to Jackie’s half-sister, Mary (Katie Finneran), who has a firmer sense of their worth but wants to keep them for sentimental value.

Several of the sentences in the previous paragraph, or perhaps all of them, contain at least one lie.

Ms. Rebeck, whose works have bounced from updated Greek tragedy (“The Water’s Edge”) to apocalyptic farce (“Omnium-Gatherum”) to social satire (“The Scene”), is looking to straddle two very different styles with “Mauritius.” (The title comes from the small tropical island that issued the two most valuable stamps — “the crown jewels of philately,” we’re told.) On one hand, we have the two-bit chiselers and gutter philosophers of David Mamet. Mr. Mamet’s “American Buffalo” (trio of lowlifes jockey for a collectible) and “House of Games” (insecure woman gets romantically mixed up with a potential con artist) were presumably not far from Ms. Rebeck’s desk, while Mr. Abraham has two monologues, one seductively indirect and one profanely direct, that could have come directly from “Glengarry Glen Ross.”

Sitting rather uneasily alongside these staccato volleys is the Mary-Jackie pairing, a dynamic familiar from kitchen-sink family dramas like David Lindsay-Abaire’s “Rabbit Hole,” which also opened at the Biltmore Theatre. (“Mauritius” also shares with that play an ostentatiously efficient set by John Lee Beatty in which a pair of turntables yield various well-appointed interiors.) The stamp collection triggers deep veins of resentment toward their dead mother and toward each other that surface during their strained exchanges.

The Sterlings of the world, needless to say, aren’t much for this sort of brooding reflection. “You’re so interested in victimhood?” Sterling sneers. “Go watch TV. That is not a world that interests me. It’s an irritant.” And so “Mautirius” takes a few tentative stabs at bridging these two seemingly incompatible realms. A blanket refusal on Jackie’s part to set an asking price for the stamps is financially shrewd, but it also bespeaks an inability on her part to make the first move emotionally, to extend an offer of romance or even of sisterhood. And Ms. Rebeck and Mr. Hughes make amusing use of Mr. Cannavale, whose maneuverings between the sisters and his secretive associates grow increasingly agitated.

But Mr. Hughes’s gift for isolating the feints and gaps in verbal confrontations, previously seen in works such as “Doubt” and “Inherit the Wind,” sputters here. Too many altercations feel dictated by the exigencies of Ms. Rebeck’s who’s-scamming-who plot, and while he and the author make worthy combatants of Ms. Pill’s and Mr. Abraham’s characters, Mr. Baker and especially Ms. Finneran are left to fend for themselves with underdeveloped characters. (Or perhaps Mr. Abraham’s gleefully over-the-top performance obscures the fact that Sterling is similarly undernourished.)

Worst of all, the fraught dynamic between the two sisters isn’t explored with nearly enough precision or insight to rival the intricate — and often enjoyable — rounds of philatelic skull-duggery. Ms. Pill, with her open face and her tense, reserved body language, makes the most of Jackie’s shifts in confidence as she gains, loses, and (perhaps intentionally) abdicates the upper hand. But not even this talented actress stands a chance with an excruciating monologue in which Jackie expresses her desire to “put those two tiny, tiny slips of paper inside my body, right where my heart is supposed to be.” If flaws really do increase the value of something, Ms. Rebeck — who inexplicably revisits this theme in a crushing thud of a finale — is sitting on a gold mine.

Until November 25 (261 W. 47th St., between Broadway and Eighth Avenue, 212-239-6200).