It's Great to Stay Up Late (Especially if You Live in a Mansion)
Later that night, Don, Cosmo, and Kathy sit around Don's dining room table and stare out the window. It's still raining. They're bummed.
Don says once the movie comes out, his career will be over. Both the movie and he are "museum pieces." He's no actor. He never was. He knows that now. Cue the Charlie Brown sad walk.
Cosmo jokingly suggests that Don can always go back to his singing and dancing vaudeville days.
Then the trio has a collective light bulb moment. What if they make The Dueling Cavalier a musical?
Problem solved. Time to sing. The three launch into "Good Morning," an ebullient song and dance number about how everything's going to be okay.
"Good Morning" previously appeared in Babes in Arms (1939), a musical comedy starring Mickey Rooney and Judy Garland.
Don, Kathy, and Cosmo dance all over Don's movie star mansion, incorporating props and furniture like their raincoats and hats, Don's bar, and so on.
Afterward, they collapse onto Don's couch in super-duper happy heap. Then it dawns on Don: What about Lina? Oh, snap.
Cosmo has an idea: What if Kathy dubs Lina's voice? They'll record Kathy doing all of the talking and singing, and then Lina will just lip sync with it.
Don doesn't want to do it because he's afraid it'll ruin Kathy's nascent career. Kathy says it's okay: It's just for this one movie, and it'll save Lockwood and Lamont. Don agrees. This one's a keeper, Don.
Cut to the front of Kathy's building. Don's escorted her home. He kisses her goodnight and then turns to head back to his house. It's still raining. Coming down hard, in fact. But Don's so blissful that he doesn't care.
In fact, he's so gosh darn happy that he launches into the title number, "Singin' in the Rain," chucking his umbrella and dancing all over the wet street.
"Singin' the Rain" previously appeared in the movie TheHollywood Revue of 1929, an all-star revue of performers who were under contract at MGM. Productions like this were pretty common back in the giant studio days.
As he sings and dances, Don's so full of joy (and water) that he's even unfazed by a glowering cop. He wisely decides to move along, though, handing his umbrella off to a stranger. Don is one seriously ecstatic, seriously soaked dude.