It’s Not the Music. It’s Not the Lyrics. It’s the Drama.

“Where you going?” a man asks the woman leaving his bed one morning — possibly expecting her to say, “to the bathroom.”

Instead she says, “Barcelona.”

Or, rather, she sings it, because the joke as well as the character insight — she’s a stewardess — are part of a song that became its own three-act mini-drama in the 1970 musical “Company.”

Act One: Bobby, the man, tries to get April, the stewardess, to come back to bed but fails.

Act Two: As April puts on her uniform, Bobby rhapsodizes about her being a very special girl — “and not because you’re bright.” (He quickly corrects himself: “not just because you’re bright.”) Then, on a ringing high note, he calls her June.

Act Three: When she accedes to his relentless importuning, he is instantly horrified. “Oh, God,” he sings, having achieved the companionship he never wanted. Blackout.

What just happened? In the three minutes, 93 bars and 181 words that make up the song “Barcelona” — one of 15 or so in “Company” and more than 750 in the catalog of Stephen Sondheim — theatergoers get a complete narrative, within the larger one of the show, that deepens our understanding of Bobby, bachelorhood and the push-pull of otherness. The director (in the original production, Harold Prince) gets something too: a rich scene to stage; the actors, a palpable conflict to play and the subtext to inform it.

And all this is done in classical A-B-A form, to a sweetly lazy tune befitting the morning-after setting, with apt but gentle rhymes (“going”/“Boeing”) and punch lines that are not just punches. They help you sympathize a little more with Bobby, even if you like him a little less.