CAMBODIANS PUNCH : ROCKING BAND *REALMS!

''GENOCIDE - genocide, genocide .........................

THEATER REVIEW : An ambitious play enacts the unresolved trauma left by a genocidal regime.

Clap your hands, everybody, and sing long with Pol! That's as in Pol Pot, the leader of the genocidal regime in Cambodia, which wiped out nearly a quarter of that country's population during the second half of 1970s.

All right, to be exact, it's not Pol himself who's shaking a tambourine and urging the audience to get up and dance at the Pershing Square signature Center in New York, where Lauren Yee's adventurous, totally scrambled ''Cambodian Rock Bank'' opened recently.

Instead, this enthusiastic master of ceremonies is called Duch. that is the nom de guerre of the former math teacher Kang Kak lew, a Pol confederate known as ''Cambodia's Himmler,'' who ran the notorious S21 prison [ tread : deadly death ] camp.

The real Duch, who was the first of the Khmer Rouge leaders to be tried for mass murder, is now serving a life prison sentence.

But Yee, a playwright of great heart and audacity to match . has seen fir to give her version of  of Duch the run of her brash but conventionally sentimental play, which features the songs of the Los Angeles-based Cambodian surf rock group Dengue Fever.

Duch is bravely portrayed by Francis Jue with a flaming archness that neither he nor Chay Yew's production can quite pull off.

Think of him as a combination of the creepy Weimar-era M.C. from ''Cabaret'' and the antic Hitler  from the recent Oscar nominee ''Jojo Rabbit,'' and you'll understand that Jue's assignment is not an easy one.

''Genocide, genocide, genocide - boo!'' Duch says, taunting us with a full dose of snark, in his opening monologue. He proceeds to ask us, with justification, ''Are you confused? Welcome to Cambodia, 2008!''

That's the year in which Duch's trial begins. And in Yee's fictionalized  evocation of that time, Neary [an earnest Courtney Reed] a young American NGO worker of Cambodian descent - has stumbled upon crucial evidence.

It was thought that only only seven people had survived their time in S21. But Neary has unearthed a photograph that suggests there may have been an eighth.

And who might he or she be? Oh, dear.

This is where the Code of the Spoilers dictates that I become evasive. But it's pretty much impossible to discuss this play without disclosing its essential plot twist, which, after all, is revealed fairly early.

The sadness of this publishing, continues. The World students Society thanks author Ben Brantley.