Andy's in a community theater production of Sweeney Todd, and he wants the whole office to come. But especially Erin, hoping it'll make her fall in love with him again. But his attempts to drum up attendance backfire, because Michael's pissed that he didn't get cast, and the only babysitter Jim and Pam can find is… Erin.
Still, everyone else shows up, so they're all there to witness Andy's singing triumph. And also his opposite-of-triumph when a cell phone goes off in the second act and it's Andy's, while he's onstage. Michael also disrupts the show by bringing balloons, dropping a wine bottle, and booing during the curtain call, but at least he wasn't onstage. Erin also messes things up by showing up with Cece, although Andy's pretty thrilled that she made it at all. The only thing that works is the early stages of Angela's cunning plan to make Dwight fall for her again by dressing like a farm girl and playing hard to get.
In the end, Andy gets over his dual disappointment (Erin went back home to Gabe, after all) by giving a private command performance to the rest of his coworkers, his favorite audience. And in the very end, we see highlights from the marathon audition that inexplicably failed to land Michael a part.
Andy comes into the bullpen wearing a sailor suit and starts singing "The Ballad of Sweeney Todd" (from the musical Sweeney Todd, coincidentally), but it's not until another cast member joins him that Jim says, "Yes!" like this is exactly what he's been waiting for all week. Between verses, Erin asks Andy if he wrote this. And then the entire rest of the company comes in singing and wielding their prop knives, which makes Dwight ready for a rumble. The musical's whole cast does a group talking-head in which Andy cockneys that they're doing "a bi' o' viral marketing, guv'nor!" At the end of the number, people applaud, Michael more excitedly than anyone. Although he wonders why no one called him after he auditioned. "Who am I playing?" he asks. The awkward pause lasts all the way into the credits. At least.
Andy presents Erin with a pair of tickets for closing night, but he's psyched to hear that Gabe can't come, because that fits into his plan to make Erin fall in love with him again. "Women cannot resist a man singing showtunes," Andy THs. "It's so powerful, even a lot of men can't resist a man singing showtunes." Back at reception, Andy tells Erin that everyone in the office is going, despite what Gabe might have said. Michael comes out and says he can't make it, because he's still bent out of shape about not being cast. Jim and Pam's babysitter fell through, and Dwight says, "The last time I went to the theater, a man dressed as a cat sat on my lap." Is that man still alive, or did Dwight stick him in the freezer?
Andy goes into Michael's office to plead with him to come, but Michael's still so hurt that he doesn't even let himself do a "that's what she said." But after hearing that they brought in a ringer to play the lead, Michael gives Andy the explanation that he'll be too busy seeing a friend in a play called Sweeney Todd. Andy celebrates, and Michael magnanimously says, "And, scene."
Angela wants Dwight to take her to the play, but Dwight wants to just "knock this out now. Disrobe." He THs that he doesn't like her any more. "Just contractually obligated to make a baby with her." When she refuses to let him punch her card (still not a euphemism) until after the play, Dwight agrees to take her on the threat of re-mediation, but Angela THs that she wouldn't mind if Dwight developed feelings for her, as per item 7C, clause 2. I would mind. I want more Isabel.
Andy finds Jim and Pam and gets them -- well, gets Pam -- to agree to keep looking for a babysitter. "Who knows, maybe I have a niece my family never told me about," Pam says. Andy thinks that would be amazing. "For a lot of reasons," Jim agrees.