During "the final dress rehearsal," it is thought that "the show, so far, is weak - it's all up to that jazz singer to put it over!" In his dressing room, Jack tells Mary: "There's only one thing on my mind - to make good tonight!" As he puts on his blackface makeup, he describes his enthusiasm, "I'm going to put everything I've got into my songs," while betraying concern for his ailing father. Mary thinks that he is preoccupied with worry: "I'm afraid you're worrying - about your father." Jack reassures her: "I'd love to sing for my people - - but I belong here. - but there's something, after all, in my heart - maybe it's the call of the ages - - the cry of my race." Mary feels he would rather be on stage: "I think I understand, Jack - but no matter how strong the call, this is your life."

In a mirror, Jack imagines his father singing in the synagogue, and his heritage calls to him: "The Day of Atonement is the most solemn of our holy days - - and the songs of Israel are tearing at my heart." Mary urges him to remain with the show: "Your career is the place God has put you. Don't forget that, Jack." Jack reaffirms the importance of his career: "You're right. My career means more to me than anything else in the world." His career means even more than Mary herself, and Mary encourages him: "Then don't let anything stand in your way - not even your parents, not me, not anything!"

Yudleson, with Sara, returns to the backstage area to speak to Jack, but they are told: "No one can see him now. It's almost time for his entrance." Sara begs: "But his Papa is sick - maybe dying - I've got to see him!" So they are let into Jack's dressing room. At first, Sara doesn't recognize him in blackface: "Jakie - this ain't you?" Yudleson is also confused: "He talks like Jakie - but he looks like his shadow." Then she tells him that his father is ill and dying: "Your Papa is so sick - his face so pale - - he calls for you." Just then, Jack is told to ready himself for his dress rehearsal performance: "Better get ready, Jack - - it's your spot next."

Sara continues: "In his dreams he hears you singing. In two hours the sun will be out of the sky - Atonement begins - - come home, Jakie." Jack is distraught, torn between his opening night in his show business career and his deep feelings for his father: "Mother, I can't - I can't!" She makes a final heart-wrenching comment: "Maybe your Papa is dying - maybe he won't ever hear you sing again." Jack's producers are also urging him to get on stage: "Hurry Jack! This dress rehearsal's just as important as the show tonight!" Jack goes center stage and sings with deep feeling 'Mother of Mine,' a song of mother-love.

Mother of Mine, when friends all doubt me, I still have you...Mother Divine, with your arms around me...When things go wrong, and they don't want me, Mother I still have you. Mother of Mine, when friends all doubt me, I still have you...

Mary, Sara, and Yudleson watch from the wings. Yudleson observes: "Just like his Papa - with the cry in his voice." With tears in her eyes, Sara begins to understand Jack's calling: "Here he belongs. If God wanted him in His house, He would have kept him there...He's not my boy anymore - he belongs to the whole world now," and they leave before he finishes performing his song.

Jack's producer feels his rehearsal number is "wonderful," but Jack is dismayed to find his mother has gone. Mary explains how his mother has accepted his show business role: "But she is reconciled and understands your place is here." After intense soul-searching, Jack returns to his home after the rehearsal. At his mother's side, she asks if he came to sing. "No, Mama," he replies, "I came to see Papa." At his Papa's bedside, his father tenderly touches his son's head and face. He tells his father: "You'll soon be all right again, Papa," and they begin to be reconciled when his father confesses: "My son - I love you - ."

When Yudleson finds Jack at home, he assumes that he has come to replace Cantor Rabinowitz in the synagogue for Yom Kippur: "I knew you'd come. The choir is waiting." Sara encourages him as a way to heal his father: "Maybe if you sing - your Papa will get well - ." But just then, the producer and Mary arrive to urge him to return with them to the opening of "April Follies." Mary asks him: "You're not thinking of quitting us, are you, Jack?" His producer threatens that his career will be ruined if he fails to appear on opening night: "You'll queer yourself on Broadway - you'll never get another job."

Jack realizes what a momentous choice he has: "It's a choice between giving up the biggest chance of my life - and breaking my mother's heart - I have no right to do either." Mary reminds him of his former words: "Were you lying when you said your career came before everything?" Yudleson pressures him too: "You must sing tonight." Jack is uncertain about that possibility: "I haven't sung Kol Nidre since I was a little boy." Yudleson assures Jack: "What a little boy learns - he never forgets." The producer warns: "Don't be a fool, Jack!" Jack turns to his mother, who tells him to "do what is in your heart, Jakie - if you sing and God is not in your voice - your father will know." The producer reminds Jack of his career: "You're a jazz singer at heart!"

At curtain time, an announcement is made to the audience: "Ladies and Gentlemen, there will be no performance this evening - - " For one night, Jack becomes Jakie Rabinowitz, singing "Kol Nidre" (in whiteface) in the synagogue in his father's place, forcing the opening night cancellation of the show. His father listens from his deathbed to the nearby ceremony. Now that his son is reconciled to the old world's values and to the family, Cantor Rabinowitz's last forgiving words are: "Mamma, we have our son again." In a super-imposed image, we see the spirit of Jack's father at his side in the synagogue. Mary describes Jack perfectly: "- a jazz singer - singing to his God."

"The season passes - and time heals - the show goes on." The show is postponed, but opens successfully the next day. Jack sings jazz in the opening theatre performance, the day after his father's death. In the final scene, his proud mother sits in the crowded Winter Garden Theater audience, listening and weeping. In blackface (symbolic of his assimilation into the culture, or a way to mask his ethnicity?), Jack croons the song "My Mammy" to her:

Mammy! Mammy!
The sun shines east. The sun shines west.
But I know where the sun shines best.
Mammy! Mammy!
My heart strings are tangled around, Alabamy.
I'm, I'm a comin'! Sorry I made you wait.
I'm, I'm comin'! I hope and pray I'm not late.
Mammy! Mammy!
I'd walk a million miles for one of your smiles!
My Mammy!

And then, Jack gets on one knee for the finale to his Mama, flinging his arms out toward her and the world:

Mammy! My little Mammy!
The sun shines east. The sun shines west.
But I know where the sun shines best.
It's on my Mammy I'm talkin' about.
Nobody elses.
My little Mammy!
My heart strings are tangled around, Alabamy.
Mammy! I'm comin'!
I hope I didn't make you wait!
Mammy! I'm comin'!
Oh God, I hope I'm not late.
Mammy! Don't ya know me?
It's your little baby!
I'd walk a million miles for one of your smiles!
My Mammy!