On Your Toes marquait la première fois qu’un musical de Broadway utilisait dramaturgiquement la danse classique et incorporait le jazz dans sa partition.
On a vaudeville stage, Phil Dolan II, his wife Lili, and his son Junior perform their nightly routine, but afterwards in the dressing-room, the parents tell Junior that he has to go to school. Fifteen years later, as predicted, Junior is a music teacher at Knickerbocker University. He has two talented students: Sidney Cohn and Frankie Frayne. Sidney has written a promising jazz ballet which Frankie catches Junior dancing to alone in the classroom (uncovering his "secret past"), and she trades an introduction to the Russian Ballet's manager in return for his listening to her song.
In the apartment of Vera Baranova, star of the Russian Ballet, Peggy, the manager, enthusiastically tells Sergei, the company's director, about the new jazz ballet. He is not interested in anything new - he doesn't even recognise that the Revolution has happened! Junior arrives as Vera and co-star/unfaithful lover Morrisone are having a Russian screaming match. The others leave, so that Vera and Junior can discuss the new ballet, but that leads to a new entanglement.
Back in the classroom, Frankie is jealous of Junior's stories about Vera and the Russians (Peggy has promised him a chance to dance in the corps de ballet), and they both wish they were away from it all. At the opening of the ballet, La Princesse Zenobia, Junior is told that one of the dancers is in jail and he has to take his place, but onstage he gets all his steps, rhythms and positions cock-eyed and makes a laughing-stock of the ballet. But the audience loves it, nevertheless.
Sergei, Peggy, Vera, Morrosine and Junior have listened to the jazz ballet. Opinions are mixed, and Vera and Morrosine are still arguing, as he becomes increasingly jealous of Junior. Poor Junior has got love problems, too: he upsets Frankie by going to lunch with Vera (for business reasons) instead of her, but she is "Glad to be Unhappy".
Then Peggy, Sergei, and some of the company visit Junior's school. Sergei has come to break the bad news that he will not be doing the jazz ballet, but Peggy persuades him by threatening to pull out the million dollars she has put into the company. After Sergei's announcement that the next production will be Slaughter on Tenth Avenue, the class put on the title number "On Your Toes", in which the students' jazz and the company's classical routines are deftly combined.
At a rehearsal, Morrosine's jealousy of Junior gets out of control, there is a fight in which he is knocked out by Sergei, and suddenly Junior is the new star. The humiliated Morrosine plots with his gangster friend, Louie, to shoot Junior at the end of the performance. Joe, the stage doorman, overhears and warns Frankie. On-stage, Junior is tipped off and signals to the conductor to avoid the final loud climax which would cover the shot, so he keeps the orchestra playing the last few bars of the music over and over as Junior dances frantically to keep the shooter from firing. Finally, he is grabbed by the police. After the curtain call, Junior is embraced by Frankie, and is startled to see his parents waiting to congratulate him. The music-teacher has made it back to his home-ground - the stage.