COUSINS in a tizzy over their late grandfather’s ‘necklace’ on the night of his funeral seems benign enough as far as plots are concerned. Yet underneath the premise of Joshua Harmon’s Bad Jews darkness lurks.

Who is most deserving of the necklace? Bossy, overbearing, holier than thou ‘Uber Jew’ Daphna? Notorious ‘bad Jew’ Liam, who has just returned from a skiing trip with his non-Jewish and rather vapid girlfriend Melody? Or Jonah, his bashful brother, who would prefer not to get dragged in to the quarrel.

The necklace bearing their Poppy’s chai, which he managed to conceal from his persecutors under his tongue throughout the Holocaust, soon becomes a symbol of their faith, allegiance and identity.

Begrudging Liam for blatantly renouncing, as she sees it, his Jewish heritage, and flouting their people’s most cherished traditions, Daphna throws her unflappable faith around like a well honed knife, spewing harsh truths like venom. Equally brutal Liam’s barely veiled jibes take a vicious turn, picking the glaring holes in her self-righteousness.

Alisa Joy is spectacular as the simultaneously insufferable and surprisingly touching Daphna, a misguided student weighed down in many ways by the bulk of history, and her perceived duty to perpetuate tradition in an increasingly secular world. Daniel Boyd is her match in every way as Liam, a complex young man whose apparent indifference reveals more about his ambivalent feelings toward his Jewishness than she suspects.

Through his barbed dialogue and motley characters, Harmon asks problematic questions about identity: what does it mean to be Jewish, ethically and religiously? How is one’s faith or commitment measured? Does it matter?

As these hang in the air seemingly never to be answered, the truly stupefying final scene is a brutal shock to the system, an emotional bombshell.

Branded as a comedy, Bad Jews is a wolf in sheep’s clothing. It personally left me in a flood of tears.

Bad Jews is on at the Theatre Royal Bath until Saturday.