The title character of the new play Bengal Tiger at the Baghdad Zoo is pretty pissed off. His country is in ruins, with death and destruction all around him. He’s still locked up in a dilapidated zoo. And when he follows his true nature by chomping on a bored U.S. soldier (Glenn Davis) who foolishly sticks his hand in his cage, he gets shot dead for his troubles.

As you probably already know, said tiger is being played by Robin Williams. The star is made to resemble an animal only through shaggy, matted hair and unkempt clothing. But he still speaks in those immediately recognizable comic rhythms, making his titular character seem less like a fearsome beast than a crotchety elderly man complaining about the conditions at his nursing home.

The movie star casting, although undoubtedly necessary for commercial reasons, seriously unbalances the overall effect of Rajiv Joseph’s surreal drama, a finalist for last year’s Pulitzer Prize. While Williams is admirably restrained in his relatively supporting role and gives a thoroughly credible performance, his presence only tends to emphasize the flaws in this thematically ambitious but unfocused play.

Set in the war-torn city in 2003, the play concerns the aftermath of the violent incident, as the ghost of the tiger wanders through the environs railing about God’s injustices.

Other characters who figure prominently in the story are Kev (Brad Fleischer), the soldier who killed the tiger with a gold-plated gun he appropriated from the former palace of Saddam Hussein’s thuggish son Uday (Hrach Titizian), and Musa (Arian Moayed), an Iraqi translator who previously worked as Uday’s resident gardener.

Past and present events are freely intermingled as the tiger ponders the meaninglessness of life even as he enters a Garden of Eden that in actuality was Uday’s ornate topiary garden. Meanwhile, Musa is forced to ponder his own role in his country’s tragic fate when he is faced with the ghost of his former employer.

The tiger’s running narration--which range from comic one-liners (“I get so stupid when I get hungry,” he admits about the incident that caused his demise) to existential musings. “When an atheist suddenly finds himself walking around after death, he has got some serious re-evaluating to do,” he admits.

The playwright certainly displays a flair for poetic language, and he has created a spooky, Beckett-like surreal atmosphere well befitting his subject matter. But there’s little narrative or thematic coherence to the proceedings, resulting in some undeniably fascinating moments that ultimately don’t add up to very much.

Director Moises Kaufman has provided a wonderfully spooky staging, albeit one that would probably have greater impact in a more intimate theater. Adding to the production’s impact are Derek McLane’s hauntingly abstract sets and the consistently excellent performances by the supporting cast. 

But it’s hard not to wish that all of this effort, not to mention the Broadway acting debut of its headlining star, had been put in the services of a more fully realized work.  

Richard Rodgers Theatre, 226 W. 46th St. 212-307-4100. www.ticketmaster.com.