Cut to the premiere of The Dancing Cavalier. We're back at Grauman's, just like at the very beginning of the movie.
We catch the tail end of Cavalier on the big screen. It looks good. It sounds good. The audience loves it. "Lamont! What a voice!" one woman says. Ugh.
When the movie ends, the curtain closes and Don and Lina enter from stage right to thunderous applause. Backstage, Cosmo and Kathy congratulate R.F. He congratulates them right back, and says the studio owes them a lot. Gee, R.F, ya think?
Don and Lina come off stage. Cosmo tells Lina she was fabulous and "sang as well as Kathy Selden." Sick burn, Cosmo.
Lina says she's going to sound that good for a long time, and Don's all like, "Say what?!"
Lina reminds R.F. that she has him over a barrel: He's going to have to let Lina keep lip-syncing to Kathy's voice because of the money.
Rod the publicity guy reluctantly agrees; they're sitting on a goldmine here.
Kathy interrupts: This is up to her. It's her voice and she just won't do it. Lina reminds Kathy that she's under contract and has to do whatever R.F. says.
Don claims that if Lina gets her way, he'll walk.
Don has a point. He's just as valuable as Lina. R.F. doesn't know what to do. Shocker.
Lina challenges R.F.'s authority and says that, as far as she's concerned, she's running things now, not wimpy ol' R.F. Yup, that does it.
Just then Rod tells Don and R.F. that the audience is waiting for somebody to make a speech. Lina says she's going to do it. She's tired of people making speeches for her.
Don thinks this is a grrreat idea, to let Lina do all the talking. R.F. and Cosmo grinningly agree.
On stage, Lina gives her speech. It's awful. For starters, her grasp of English grammar isn't so hot. Second, there's that voice.
The audience wants to know what in the heck that unholy sound is coming out of her mouth. They tell her to cut the talk and start singing. Lina looks worried.
Backstage, Don says he has an idea and pulls Cosmo and R.F. aside. They huddle up. We can't hear what they're saying.
Lina rushes backstage, frantically asking what she should do. R.F. says they'll set a microphone up behind the curtain and have Kathy sing. Lina will lip sync out front, just like in the movie.
Kathy doesn't want to do it. Don and R.F. both sternly tell her she has to. Kathy's all confused and says she'll do it, but she never wants to see Don again. Way to blow it, Don.
Kathy and Lina take their places. They're going to do "Singin' in the Rain." The orchestra starts. Kathy sings. Lina lip syncs. Don, Cosmo, and R.F. mimic Lina's cheesy dance moves.
Then, at just the right moment—and unbeknownst to Lina—they lift the curtain, revealing Kathy to the audience, and exposing Lina as a fraud.
The audience launches into uproarious laughter. Kathy looks worried. Lina's oblivious. Cosmo comes out and takes over singing for Kathy.
Kathy tearfully runs off stage and up the aisle toward the exits. Don runs on stage and directs the audience to stop her. He also tells them that she's the real star of the movie.
Kathy turns around, and Don starts singing "You Are My Lucky Star." Cosmo takes over for the orchestra conductor, of course.
The ballad "You Are My Lucky Star" has the same previously used pedigree as "Broadway Rhythm": it appeared in both Broadway Melody of 1936 and Babes in Arms (source).
Kathy returns to the stage and duets with Don. Guess she's not mad anymore.
As Don and Kathy gaze at each other, we zoom in on Don's profile. The shot dissolves into a painting of Don. We zoom back out and see that it's part of a billboard for a new Monumental Pictures production: Singin' in the Rain starring Don Lockwood and Kathy Selden.
Don and Kathy stand in front of the billboard, admiring it.
Incidentally, can you imagine driving by a billboard for a new Brad Pitt and Angelina Jolie movie and spotting the two of them standing there in front of it, admiring their own giant faces? Us neither.
Don and Kathy stop admiring their massive movie star heads and embrace. They kiss. The music crescendos. And that's all, folks.