"Prologue" Early morning, St. George Hotel on New York City's Upper East Side. Jenny Steinberg appears to be a bride, sitting alone in front of a mirror, wearing a wedding veil. She examines items on the vanity in front of her while insisting "I Never Wanted This!"

The members of the Steinberg/Howard wedding party and the St. George Hotel staff begin preparations for the wedding that's happening on "This Day." Rebecca starts to have a meltdown when she gets a smudge on her wedding dress. Jenny assures her that it's all going to be "Perfect."

Marty Kaufman, the bride's ex-boyfriend, shows up at the hotel, looking for Rebecca but running into her parents. Instead of being angry at him for showing up uninvited, they say, "It Shoulda Been You," and encourage him to win Rebecca back.

Marty begs Jenny to just let him talk to Rebecca. He even tries to guilt her into it by reminding her "Who" used to be her best friend when they were growing up together.

Marty overhears George's attempts to bond with Brian by confessing that he wished he had been friends with his own father "Back in the Day." Once they bond, George hands Brian a prenup. Marty runs off to tell Rebecca about the prenup, hoping that it will convince her to call off the wedding.

Judy has invited Georgette to have her hair done with "us girls" at the Hotel's Hair Salon, so that she can "lay the groundwork of their future relationship." When Jenny finds out what her mother has planned, she warns her that she better be nice. Judy assures them that she'll be nice... the best she can. Jenny insists that Judy be nice Georgette's way, or they will never forgive her. Judy agrees, but we soon find out just how much it costs her to be "Nice."

Marty runs into the salon and tells Rebecca about the prenup. Georgette swears to Judy that she didn't know anything about the prenup, but Judy doesn'tbelieve her. The battle lines are drawn, and Jenny can do nothing but watch as the wedding into which she put her heart and soul falls apart. Now, it's "Albert's Turn" to step in and fix it.

Brian stops by to check on his mother. While there, he lets her know that, if he ever achieves anything in this world, it will be because of her. He loves her. Georgette tells him that she loves him, too: "A mother couldn't ask for a more perfect son." But, when he leaves, she wonders "Where Did I Go Wrong?"

After Jenny overhears her mother making fun of her weight, she longs for someone to tell her that she is "Beautiful." After they tie the knot, Brian and Rebecca burst into their private room, the Chedar Yichud, relieved that the ceremony was "A Perfect Ending" to all of the mishegas. Members of the wedding party enter different areas of the hotel and share their own feelings about what's happened so far, as Greg and Annie sneak into Brian and Rebecca's room for a little private celebration of their own. When Jenny and Albert walk in on Brian kissing Greg and Rebecca kissing Annie – long, loving, sexy kisses, the kind that make straight people squirm – Jenny drops the tray holding the champagne glasses. Albert and Jenny agree not to say anything, and everyone heads into the reception, where Greg and Annie perform "Love You Till the Day," a song they'd written earlier for Brian and Rebecca. When Judy asks Jenny to make sure the photographer takes a picture of Rebecca dancing with their father, Jenny says no and leaves the reception. Judy follows, wondering why Jenny won't do that little thing for her sister. And that's it. Jenny can't take it anymore and unleashes "Jenny's Blues."

Judy asks Marty to check on Jenny because she's acting so strangely. Jenny grabs Marty and kisses him full on the lips – a long, loving, sexy kiss, the kind that makes gay people squirm. Jenny pulls back, realizes what she's done, screams and runs into the ladies room, ultimately hiding in a stall when Marty follows her. Jenny thinks Marty is still in love with Rebecca, so when Marty blurts out that Rebecca's gay, Jenny is confused. It's always been Marty and Rebecca/Rebecca and Marty. Marty reminds her that "before you went away to college, it was me and you." Jenny scoffs that he was never in love with her. Marty says that, no, he was never in love with Rebecca. Jenny wants to know what he means by that. He wants to know what she meant by kissing him earlier. She says that she meant, "Whatever," then runs back into the stall and locks the door. Marty tells her what he hopes "Whatever" means, and she comes out of the stall. Marty and Jenny start kissing for real, but are interrupted by Albert, who comes in to tell them that he thought they'd like to know that Rebecca is about to tell her parents that she's gay. After they all run out, Aunt Sheila pops her head up out of another stall, delighted to have found out that Rebecca is a lesbian. Walt pops up next to her, hoping that they can finish "Whatever," because he's got tables to bus.

Rebecca tries to explain why she didn't tell people that she was gay before, and why, if she doesn't tell them now, she'll be "A Little Bit Less Than." For Brian's sake, Rebecca decided to wait on telling her parents, but Aunt Sheila lets the cat out of the bag. Once their plot is revealed, it appears that the wedding is over until Marty proposes to Jenny, whom he has loved since he was six years old. Jenny loves him, too, but says no, this is not the way it's supposed to happen. Judy says here's "What They Never Tell You" – when it comes to love, there's no such thing as "supposed to." Jenny says yes to Marty, and the four lovers, so moved by Judy's speech, decide that they want to get married, too.

As they run off to discuss the details with Albert, the four parents wonder what the hell just happened. Oh, wait, no, they don't, "That's Family." Everyone gathers to watch as Jenny enters, looking radiant in her new wedding dress. Judy tells Jenny that she looks "Beautiful," and Marty wholeheartedly agrees.As they head down the aisle, Jenny pauses to say "I always wanted this." ("Finale").