I am happy to report that there was Jameson's on offer and there was an Irish bartender downstairs, but that the opening-night party for "Blood and Gifts" at P.J. Clarke's, across from Lincoln Center, featured no green beer. To explain why that matters I must divulge a detail, not a spoiler, from J. T. Rogers' completely absorbing play itself: the drama contains a scene at the Irish embassy in Islamabad, Pakistan, and emerald-hued lager is hoisted. 

I didn't quite catch what Michael Aronov, who plays a KGB operative in the show, was drinking, but I did hear him say, as he glided across the restaurant holding a plate of food, "It's like a disco in here." I couldn't tell if that was meant as scourge or support for the invisible d.j. spinning the upbeat platters. I also didn't stay at the affair quite wee-hour-y enough to see if Aronov moved rhythmically to the tunes as dexterously as he does to the Irish-embassy noise in "Blood and Gifts." 

I did, however, stick around long enough to chat with Pej Vahdat, who plays the character Saeed. "It's quite a night, isn't it?" he said. "It's such an honor to be in this play. For us actors, it's like a relay race. Everyone passes the baton to everyone else, scene to scene." Vahdat told me that his parents had come in from California for the opening. "It's great to have them here." 

As "Blood and Gifts" is a play about recent history, let me make a note about P.J. Clarke's and its recent history with Lincoln Center Theater events. The "Blood and Gifts" party did not have the in-the-family coziness of the gathering for the production's first preview, held there three weeks ago, and this week's party lacked the whoops and hollers of the Tony-awards party there this past June, which saw "War Horse" win five statuettes. 

What the event did have, in profusion, amidst the celebratory mood, was a lot of intelligent talk about the play itself. I had conversations with an educator about what the drama's subject matter would mean to New York's increasingly diverse high-school students; with an historian about the number of casualties that the Soviets sustained during their Afghanistan war; and with an actor about the way in which the "war on terror" undertaken by the U.S. during the Bush years had its roots squarely in what happened in the events of "Blood and Gifts." Finally, a "War Horse" actor brushed past me at one point and blurted, "The play was so interesting - and I had no idea it would also be so entertaining!" 

So much good talk amidst so much good cheer: that's a rare thing for a party, even in New York where everybody has an opinion about everything. But that everything is rarely something as engrossing as what we witness in "Blood and Gifts." And it was gratifying to see, as I left the party and started reading the play's reviews on my iPhone, that the reviewers agreed with the partygoers' electric assessments. 

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.