After some preliminary bitching from Derek (Jack Davenport) and surreptitious handholding from Julia (Debra Messing) and Michael (Will Chase), who consummated their adulterous affair last week, we get to Katharine McPhee's obligatory pop number as her character, Karen, has a recording session, which she scored based on her bar-mitzvah gig last week. Back to the rehearsal studio, where Tom (Christian Borle) catches Julia and Michael canoodling, and who should be hidden in the corner but the show's own Eve Harrington—Ellis (Jaime Cepero), Tom's sneaky assistant. What is it with Ellis that he's always in exactly the right place to overhear juicy secrets?
Ivy then arrives at the studio with her mom in tow. With remarkably little prompting from the fawning chorus kids, Lee launches right into "Everything's Coming Up Roses." No warm-up, no scales, nothing. She just interrupts a vital rehearsal on the last day before a major workshop and delivers a Broadway-level performance of a showstopper. Halfway through the number, Ivy gets all uncomfortable-looking (subtext: "Why does mom always have to steal my spotlight?"). Then, in the middle of another number, leading man Michael gets an unexpected visit from his wife and tiny son, just to turn the knife in Julia's guts. What is this, family week? For once I sympathize with snarky Derek; his cast and creative team are falling apart on him just before the big show.
Julia has an attack of the guilts and runs home to find her son, Leo (Emory Cohen), smoking pot. He turns the tables by confronting his mom with his knowledge of her affair. Meanwhile, Ellis blabs to producer Eileen (Anjelica Huston) about the hanky-panky, and she finally puts him in his place, then attempts to deal with the studio's broken boiler, which is making the venue uncomfortably hot.
Evidently Ellis knows about plumbing in addition to real estate, as he and Eileen wind up back at their favorite cheap bar discussing how to find a plumber to fix the boiler. The cute bartender justifies his cameo from last week by offering the services of a friend to do the job. Then we get a montage of everyone in bed the night before the big workshop. By the way, what is Tom doing sleeping with his on-again, off-again boyfriend John (Neal Bledsoe)? I thought they had rotten sex two weeks ago.
The next morning Eileen gets all tough and batters the lock on the boiler room, with the bartender and a bushy-bearded plumber accompanying her. With Ivy conveniently stuck in an elevator, Julia steps in to read with Michael a Marilyn-Joe scene from the show that parallels their relationship. The tortured lovers end up improvising something new in front of everybody, which Derek then instructs the stage manager (poor Ann Harada, who never gets a scene) to write down (like she'd remember it).
Just before the workshop starts, we get the vitally important plot development of Tom learning that Sam (Leslie Odom Jr.), the sports-loving chorus boy, is not straight. Tom gets all hot and bothered, and romance is foreshadowed.
The performance finally starts, and Peters has a close-up in which she showily weeps as Lee watches her daughter play Marilyn. We get a medley of all the songs we've heard in previous episodes and a new song—"Lexington and 52nd"—in which Joe expresses his dissatisfaction with his marriage to Marilyn, just like Michael is frustrated with his incomplete union with Julia, get it? And just in case you don't, there's a fantasy sequence with Michael singing it just to Julia.
The air conditioning kicks on after that number (I thought it was the boiler that was broken). The workshop gets a mixed reaction, and Ivy has a teary confrontation with her overbearing, undemonstrative mother, accompanied by an arty shot with mirrors. But mother and daughter also have a tender farewell scene, with Peters getting to cry some more. Julia, Tom, Elaine, and Derek conduct a postmortem on "Marilyn," and the show's future is uncertain. They decide to fire Michael, not because he wasn't great as Joe, but because his presence threatens Julia's marriage. Then Julia goes home and informs Leo about Michael's fate. "He wasn't right," she says, with Messing imparting layers of subtext to the line. Leo bursts into tears, and I notice that their kitchen has an enormous refrigerator.