New York, 1935. Kitty O'Kelly is a Broadway star who is dumped by her boyfriend after a night of heavy drinking (Down in the Depths), setting off a chain of social adventures among a tight-knit circle of entertainers. In a parallel thread, Italian gambler Johnny Spanish wins a poker game and returns to his shabby downtown apartment (Tomorrow), while spoiled heiress Brooke Carter comes back to her hotel suite after a night out, only to be handed an eviction notice by her maid, Elizabeth. Meanwhile, playboy millionaire Michael Oliver Pritchard III sweeps home with his chauffeur and valet, Rodney James, after more nocturnal partying (Poor Young Millionaire). The morning after, Kitty rushes out, mistaking Michael’s limousine for a taxi, and though Rodney tries to avoid trouble, he still causes a minor accident. Michael and Kitty instantly click, while Brooke and Kitty’s path begins to tangle with Johnny’s.
Brooke and Elizabeth head to the race track hoping to raise money to cover the hotel bill. They meet Johnny, whom Brooke immediately dislikes. Brooke bets her last $300 on the same race as Johnny; his horse wins, while hers comes in dead last. After the race, Johnny offers Brooke and Elizabeth a ride. Elizabeth declines, but nudges Brooke to accept. The mood shifts as Michael and Rodney attend Kitty’s musical and end up sitting with Brooke and Johnny. As the show kicks off, Brooke recognizes Kitty as her former schoolmate Kathy Krumm. Afterwards, Michael, Brooke, and Johnny visit Kitty backstage, and the two women reconnect. The quartet heads to a nightclub, and Michael invites them to his country house for the weekend. On the way, they pick up Elizabeth, who finds herself attracted to Rodney, much to his annoyance. They also stop at Johnny’s place, where Brooke is disappointed to learn he lives in a poor apartment building. Still, Kitty and Michael manage to lift everyone’s spirits, and they all bounce back to a more carefree mood (Friendship).
The next morning, Rodney and Elizabeth share breakfast with their employers, recovering from a night of drinking. Elizabeth tries to pursue Rodney, but the attempt goes nowhere (But in the Morning, No). Johnny apologizes to Brooke for lying and promises he’ll make a fortune soon. When Brooke remains upset, Johnny goes for a walk and crosses paths with Kitty, who flirts with him. Michael accidentally bursts into Brooke’s bedroom after a practical joke involving shaving alcohol (At Long Last Love). Michael’s mother, Mabel, visits and persuades them to attend a dance party at the Racquet Club; the foursome reluctantly accept. Brooke and Michael slip away to the back yard, only to be noticed by Kitty and Johnny, who quietly slip off as well (Well, Did You Evah!).
To stir jealousy, Johnny follows Brooke and Michael, posing as a couple in front of them. Brooke agrees to play along, but the “fake” couple ends up spending a night at Brooke’s place (From Alpha to Omega). The morning after, Brooke and Michael return to the country house, and Brooke openly seduces Michael—an affair that succeeds (Let’s Misbehave / It’s De-Lovely). Elizabeth takes a similar liberty with Rodney by barging into his room and pursuing him (But in the Morning, No). Kitty and Johnny stage public displays of affection at a baseball game and a boxing match, leaving Michael torn by the sight of their closeness even as Brooke remains mostly unfazed.
The tension comes to a head at a movie theater where Michael and Johnny quarrel in the men’s room, only to reconcile soon after. The fallout is quick: Michael ends things with Brooke, and Johnny ends things with Kitty. Brooke retreats to her suite, while Johnny needles his way into winning money—still, he has already won a sizable jackpot, and his next move is unclear. Kitty’s own oscillating romance with Michael cools, and she purchases a horse named Kathy-O as a playful reminder of past ambitions.
A telegram from Brooke’s mother informs her of a million-dollar deposit in her account, shifting the financial balance and the choices she faces. Elizabeth pushes Brooke toward shopping, and Kitty and Brooke unexpectedly meet in the powder room of Lord & Taylor, where they forgive one another and openly voice their shared disenchantment with men (Most Gentlemen Don’t Like Love). They plan a night of dancing and shopping again, and Elizabeth calls Rodney to hatch a new plan.
In the park, Kitty laments her unrequited love for Johnny, while Brooke laments her own for Michael (I Loved Him, But He Didn’t Love Me). The trio—Rodney, Michael, and Johnny—arrive at the club, where Rodney dances with Elizabeth and finally returns her affection. Michael and Johnny then attempt to rekindle their relationships with Kitty and Brooke on the dance floor, and the pairings heal as a couple again in the closing number (A Picture of Me Without You). The dancers switch partners as requested, and the sight of Brooke at her best elicits admiration from Johnny, while Michael tells Kitty she looks more beautiful than ever.
