If words could really kill, then the stage manager at Roundabout Theatre Company's Laura Pels Theatre would have a lot of messy mopping up to do after every performance of Bad Jews, a fierce and funny clash-of-wills in which first cousins fight (if not to the death, pretty damn near close to it) over a chai that hung around their grandfather's neck.

The old boy has barely been lowered into his grave before Daphna Feygenbaum (Tracee Chimo), a Vassar senior, goes into banshee overdrive to get the heirloom from her generation's first-born male, Liam Haber (Michael Zegen), a petulant grad student who missed the funeral altogether because he was snowboarding in Aspen with his shiksa girlfriend, the ridiculously named Melody (Molly Ranson). The two square off and slug it out in claustrophobically close quarters — the studio crash-pad of Liam's brother, Jonah (Philip Ettinger), a very reluctant eye-witness.

The scalding acrimony that is then slung about with such cruel abandon and authority by these two comes from a seemingly placid place. His name is Joshua Harmon, 30, and he has all the wide-eyed, cherub-faced innocence of Jonah Hill — a clever disguise for someone so adept at writing deliciously nasty diatribes. Making his New York debut as a playwright, he wowed critics last year when this play premiered at the Roundabout Underground's Black Box Theatre. Its 62 seats sold out regularly, and now Bad Jews has been moved upstairs to the 420-seat Laura Pels.

You have to ask: what came first — the title or the play? "I wish I had a good story," Harmon said apologetically as he launched into a good story. "The title popped into my head in 2004, and that was the impetus for writing the play. I just said, 'I like this title. What could I write that would fit the title?'" Nine years passed while he thought about it, and the malice marinated into some vicious verbal mud-wrestling.

Harmon admitted, however, the title had him sweating bullets when Robyn Goodman, who produces the Underground series, summoned him to her office to discuss a possible production. "I sorta instinctively knew it was the right title, but I had no intellectual justification for it, and I was afraid she was going to ask me to change it. Two days I spent building this argument about why it had to be called this. Then, when I walked into the meeting, the first thing Robyn said to me was: 'Bad Jews — that's a great title!' Immediately, I felt safe. I thought, 'She wants the play to be what it is trying to be. She doesn't want to change it at all. She's going to take the risk.'"

	Molly Ranson and Michael Zegen in Bad Jews.
	photo by Joan Marcus

There is one little problem with the title, though: What we really have here is Jews Behaving Badly, so it's very hard to figure out exactly who the title characters are. "The chai is important to both cousins in the play — for different reasons. It had belonged to their great-grandfather, who passed it on to their grandfather, whose entire family had been killed in the Holocaust. It's the last remaining object from that family, so it has religious connotations. Daphna feels very deeply those religious connotations. Liam feels a familial connection. It was an object that had value to his grandfather, and, since his grandfather was important to him, it means something."

What's shocking about all this intrafamiy kvetching is how intimate the anger is. "Daniel Aukin's direction deepens that intimacy, I think," Harmon said. "You're voyeuristically peering into something that you should not be watching. This is a private fight within the family, and you're somehow intruding, which is an exciting, dangerous place for an audience to be. You're seeing something that is not meant to be seen.

"It was fun for me to tap into that anger. I'd never tried to be that angry before, but both of them had valid arguments and both are right at different moments. It seemed wisest to make them as ugly as possible so it never felt like one was being favored over the other. I could either pull back and make them sweet and have it be a very sweet passive-aggressive conversation, or I could say, 'The stakes are high — this means a lot to both of them at this moment in time,' and push them to their limits. I had never pushed myself in that direction with characters before."

Already, Harmon's not resting on his Bad Jews' laurels. "My next play I've been working on for two years. It was definitely inspired by Wendy Wasserstein — particularly her Isn't It Romantic — and it's about somebody whose best friends are all getting married. He's going from wedding to wedding to wedding, watching them go down the aisle. It's about what it's like to be in that transitional moment."

It's a comedy, of course, and he's calling it — what else? — The Franco-Prussian War.