Irene Sofia Lucio (Daphna) and Joe Paulik (Jonah) in the Studio Theatre production of “Bad Jews.” (Teddy Wolff)

Just as you’re advised to stand back from an electrified third rail, you might want to maintain a safe distance from Daphna and Liam, the hazardous kibitzing cousins of Joshua Harmon’s devastatingly, acidly funny “Bad Jews.”

As played with smashing acuity by Irene Sofia Lucio and Alex Mandell, Daphna and Liam are so lethally allergic to each other that you expect the set of this brutal, hilarious, quicksilver play — directed with a maestro’s keen powers of perception by Serge Seiden — to end up roped off by crime-scene tape.

Events do get carried away; you will, in fact, be shocked by the invective spewed by this pair of entitled, hyper-articulate monsters, compelled in ­Seiden’s Studio Theatre production to spend the night in a small Manhattan apartment with Liam’s girlfriend, Melody (Maggie Erwin), and his younger brother, Jonah (Joe Paulik). And courtesy of Harmon’s dramatic portraiture, you’ll wonder at the source of pain or grievance or insecurity that can uncork such volcanic animosity.

Harmon is a recent graduate of Juilliard’s playwright program, and the unfiltered vehemence of “Bad Jews” is evidence of both an exciting, youthful voice and a writer who has not yet discovered how to temper all the frantic emotional highs with a more varied spectrum of the tranquil. There does come a point in “Bad Jews” when the argument becomes so uncomfortably intense, the accusations so unforgivable, that you can’t quite believe one or other character doesn’t flee (or jump from) the Upper West Side studio apartment, drawn with winning exactitude by set designer Luciana Stecconi.

Then again, an audience is so thrilled they all stay put, because “Bad Jews” is, for lovers of dramatic organisms truly alive on a stage, great fun: red-meat theater, marinated in fearlessness.

From left, Irene Sofia Lucio (Daphna), Maggie Erwin (Melody), and Alex Mandell (Liam) in the Studio Theatre production of “Bad Jews.” (Teddy Wolff)

The title is an ironic reference to a judgment some Jews confer on themselves or on others for not being sufficiently observant: to eat on Yom Kippur, the high holy day of fasting, is to be a “bad Jew.” The play will reveal that a more apt title might have been “Jews Behaving Badly.” For Daphna and Liam are bad not by any measure of faith or lack of it, but because they allow their angry hearts to poison their estimable intellects, and in the process traumatize the gentler people in their midst, in this case defenseless Jonah and Melody. (Paulik and Erwin are both splendid in these generally less showy roles, though Erwin also gets a fabulous comic moment, befitting her character’s name, and Paulik’s Jonah has the drama’s poignantly realized — if a tad manipulative — final say.)

They’re gathered on this evening in the studio that Liam and Jonah’s wealthy parents have bought for them on Riverside Drive, down the hallway from their own (their coddling factors in as another resentment in ­middle-class Daphna’s bottomless barrel of bitterness). The sad occasion is the death of Poppy, a Holocaust survivor and their beloved grandfather, whose funeral took place earlier in the day and which Liam missed, having lost his iPhone while off skiing with Melody, a Gentile to whom he was about to propose, in Aspen.

Pleading poverty, Daphna, a Vassar senior planning to pursue rabbinical studies in Israel, stakes her claim to a bed in their apartment and, with even more convulsive repercussions, the right to inherit the religious symbol Poppy had worn around his neck since his imprisonment in a Nazi concentration camp. Little does she know that despite her stronger bond with Judaism, her contentious cousin has his own designs on the heirloom.

It’s under this emotionally loaded cloud that “Bad Jews” boils and bubbles, mostly stirred by button-pushing Daphna. The part is manna for an actress who knows how to slip in a shiv, and in Lucio, Seiden and Harmon have a virtuoso at wound-infliction; the barbs fly in her astonishingly physical performance in ways that turn trash talk into art. Daphna’s quick-draw mind is a scary weapon, and when, via Lucio, she trains it on unsuspecting Melody, a staffer at a nonprofit who (thankfully) has relinquished her opera-singing dreams, the carnage is both riotous and horrific.

The deck, admittedly, is stacked too transparently against Daphna, who, it is suggested, harbors other than familial feelings for cousin Liam, and whose outbursts are laced with hateful cruelty. Liam, a graduate student at the University of Chicago, it should be noted, is no picnic, either. Mandell proves a whiz at the aggression Liam throws right back at Daphna. Just as shamefully, Liam makes Jonah collateral damage. “You’re legitimately not intelligent,” Liam, blinded with contempt for Daphna, says to Jonah, a condemnation uttered by Mandell as if speaking to an uncomprehending lower life form. Paulik adopts the countenance of a sad human sponge, absorbing the insult as a fact of his existence.

Like a sudden hailstorm, the play unleashes its ferocious energy and is gone. What is to become of Daphna and Liam, if they don’t find some safe exit from their rage? That’s the most disturbing mystery “Bad Jews” leaves behind.

Bad Jews

By Joshua Harmon. Directed by Serge Seiden. Set, Luciana Stecconi; lighting, Daniel Maclean Wagner; costumes, Kelsey Hunt; sound, Palmer Hefferan; casting, Jack Doulin. About 90 minutes. $44 to $88. Through Dec. 21 at Studio Theatre, 1501 14th St. NW. Visit or call 202-332-3300.