The lights go down and Natasha is confused by the artifice of the opera. People are singing and the sets are cardboard and it seems ridiculous. She's intoxicated by it all, though, and all the people. Anatole Kuragin, Helene's brother comes in, impossibly handsome and notices her. He asks his sister who she is, and says "how charming", which she notices. She's excited by it all.
During the first intermission, Pierre comes over to talk, and Anatole sits in his sister's box. Any time Natasha looks over he's looking at her. Finally Helene asks for an introduction. She says she's charmed by Natasha and how can she have been hidden in the country. Countess Bezukhov was entitled to her reputation as an enchanting woman. She was able to say what she did not think, and especially to flatter, with perfect simplicity and naturalness.
By the end of the second act, when everyone is applauding for a dancer - she describes everyone as having bare legs on stage, and the countess herself being entirely exposed - she says he's wonderful along with everyone else.
Helene indicates that she knows of Natasha and Andrei's relationship, so her brother must, too, but that doesn't stop him from pouring on the charm. Hopefully Natasha will not be so bowled over by this whole world as to jeopardize her relationship with Andrei. It's clear, from the stars in her eyes, she might if she's not careful.
I love the description of theater in this chapter - a fat woman waves her arms and sings, and other people all sing at each other while backed by cardboard. At one point, the woman on stage is abducted, but not before everyone sings about it first. It's all action, and completely incomprehensible to her - another thing for Tolstoy about corrupt and fake society, I think. We'll see how it shakes out.