Antoinette Thornes and Timothy John Smith in Robert Callely’s “On a Stool at the End of the Bar,” directed by Michael Parva, at 59E59 Theaters through December 14. | CAROL ROSEGG

Antoinette Thornes and Timothy John Smith in Robert Callely’s “On a Stool at the End of the Bar,” directed by Michael Parva, at 59E59 Theaters through December 14. | CAROL ROSEGG

It might be tempting to dismiss “On a Stool at the End of the Bar,” now playing at 59E59 Theaters, as a shaky stage version of an old “ABC Afterschool Special” episode. Set in a working-class Camden, New Jersey home in the late 1980s, the drama examines the impact of a woman’s shocking secret — she was actually born a male — on her loved ones.

But this play, directed by Michael Parva, actually has some bite. Among the melodrama are some wonderfully wrenching moments, often spiked with profanity, that are truly soul-stirring. More like an “Afterschool Special” presented by AMC, not ABC.

The plot centers on hardworking Christine (Antoinette Thornes) whose life is upended when her brother (John Stanisci), from whom she’s been estranged for two decades, pays an unexpected visit and unwittingly reveals a volatile secret to her unsuspecting partner of ten years, Tony (Timothy John Smith).

Piquant melodrama about gender identity delivers vital message of acceptance

Turns out Christine’s birth name was Christopher. Feeling trapped in the wrong body and shunned by a God-fearing family, Christopher was forced to leave home as a teen and work as a hustler to save enough cash for a sex-change operation.

Tony goes ballistic and insists that he and his teenaged children (played with conviction by Luke Slattery, Sara Kapner, and Zachary Brod) move out. Although the kids are from a previous marriage, they’ve come to think of Christine as their mom.

The play boldly tries to articulate the minefield of emotions and dilemmas that come with gender reassignment: When (or whether) to disclose your past. How it directly impacts loved ones. The fear of what others will think. Whether being a transsexual means you are gay — or were gay. Not to mention the shame and self-loathing.

A macho, bearded Smith delivers the strongest performance in the ensemble. His Tony is a tangle of rage and confusion and disgust. “He thought I was a faggot too,” Tony says of Christine’s brother. Despite Tony’s tearful protests, we suspect he doubts his own sexuality, too.

Slattery is completely believable as the eldest child, Joey, a conflicted, hormonal high school student (in actuality, Slattery is a graduate of Vassar College). Joey’s outrage against Christine — as it happens, he has a little crush on her — is heart-wrenching.

“Are you really a queer?” he asks incredulously. “It’s disgusting! Why did you have to tell us?”

Thornes delivers an understated, brooding performance as the mother figure who agonizes over telling her family the truth about her past. Perhaps too calm a portrayal — I wanted a bit more passion.

We are fully invested in this family and root for them to resolve their differences. The upbeat conclusion, handled with a light touch, is pitch-perfect.

That’s not to say there aren’t some serious snags. First-time playwright Robert Callely’s script is often contrived and rarely rises above standard narrative. Many transitions are clunky, suggesting the troupe could have used more rehearsal time.

Two ancillary scenes — one where Tony seeks counsel from a bigoted priest (Robert Hogan) and another where Christine turns to her psychotherapist (Liza Vann) — go on too long and are awkwardly inserted into the play.

Faults aside, the endeavor is a welcome addition to a new wave of LGBT theater where the T is finally getting the spotlight it deserves. Currently on Broadway, for example, there’s “Hedwig and the Angry Inch” and “Kinky Boots,” also imparting their message of gender-bending acceptance.

But these are glitzy musical spectacles. By contrast, “On a Stool at the End of the Bar” is down-to-earth and more relatable. What this admirable effort lacks in polish, it makes up for with conviction and heart.

ON A STOOL AT THE END OF THE BAR | The Directors Company | 59E59 Theaters, 59 E. 59th St. | Through Dec. 14: Tue.-Thu. at 7:15 p.m.; Fri., Sat. at 8:15 p.m.; Sat. at 2:15 p.m.; Sun. at 3:15 p.m. | $35 at or 212-279-4200 | One hr., 40 mins., with intermission