George is summoned to see "several gentlemen" outside - he swaggers to the backstage door where to his surprise, young townie kids from the theater gallery hurl objects at him and scuffle with him in a fistfight. "Let's see how tough he is!" they shout. After he is rescued, George is administered first aid by his mother Nellie and his sister Josie (Patsy Lee Parsons at age 12) - he was "almost murdered in cold blood." Tongue-in-cheek, Jerry calmly mentions: "Well, the way I figure it, it's a fine tribute to Georgie's acting. The way he plays the part, every tough kid in America will want to take a punch at Peck's Bad Boy, just to see what happens." Georgie is concerned that he'll have to "go through that every night!"

Seeing his opportunity, Jerry delivers a lesson to his head-strong son about conceit and arrogance, and George promises to reform himself:

Jerry: Yes. And matinees, Wednesdays and Saturdays. Georgie, those boys did you a great favor and they saved me a lot of trouble. You know, most actors give their whole lives to their profession without once scoring a hit. You're lucky. You're a hit at the age of 13. I've been in this business a long time and I've never met a performer who, in the long run, wouldn't rather be a great guy than a great actor. That is, until I made your acquaintance.
George: Can't I be both?
Jerry: The chances are, the way you're going, you won't be either. If the hoodlums don't get you, a committee of actors will! Actors are considered a very bad risk by insurance companies. And any actor with a conceit like yours - well, we just couldn't afford the premium.
Nellie: What your father really means is you're too sensitive, you're too anxious to make good. You love the theater too much. Oh I know you can improve, if you want to.
George: Sure I can, just watch me. From now on, I'm Peck's Bad Boy only from eight-thirty till eleven in the evenings.
Nellie: That's a boy, Georgie.
George: I promise, mother.
Josie: And don't forget, Wednesdays and Saturdays, two-thirty till five.

Backstage, the Cohans are alerted by the stage manager that B.F. Keith's partner Ed Albee will visit them - Jerry exclaims excitedly: "That means big time vaudeville, Nellie. We're in the big time!" George is ushered behind the woman's dressing curtain and instructed to remain hidden and quiet. Albee (Minor Watson), a cigar-smoking show-biz promoter, proposes them for an engagement in Philadelphia:

Albee: Of course, your show is no good for vaudeville but I've seen a lot worse right here in Brooklyn. We're opening a new theater in Philadelphia - the Bijou - on the Fourth of July. Now if you can fix up a good vaudeville act, we'll double your present salary, give you ten-weeks guarantee and third or fourth billing.
Jerry: Double our salary?!
Albee: You'll be with the best variety artists in the country - Vosta Victoria, Eddie Foy, Ward and Vokes, Lottie Collins, Charlie Case -

To his parent's horror, George bursts from behind the curtain, imperiously telling Albee: "Just a second...The salary's all right, but how have you got the nerve to offer us third or fourth billing after my performance tonight?" Albee turns and asks Jerry: "Is this kid in your show?" A boastful, conceited George doesn't stop there: "Am I in the show? Who do you think was Peck's Bad Boy?" The cocky young boy insults the showman for not recognizing him: "Then maybe you're not the showman you're cracked up to be!" The deal is withdrawn and Albee hurriedly exits - the Cohans lose the job: "Maybe you're not quite ready for the big time yet."

The insolent boy is long overdue for corporal punishment, yet he mustn't be rapped on the hand ("he has to play the violin") or slapped across the mouth ("he has to sing"), according to Nellie. Jerry turns his disobedient son over his lap for a spanking: "Here's one place without any talent!"

In the next vaudeville montage, the family travels by all modes of transportation to their next series of shows as The Four Cohans - time is telescoped for the next ten years:

Nellie: Who are Lewis and Clark, George?
Young George: Acrobats? Look at the swell write-up we got in The Clipper. (He has 'lifted' a newspaper from a passing salesperson)
Nellie: Write-up?
George (Cagney's voice-over): You'd find us whenever new states sprouted on the prairie. We played every town in America that had a theater...[Superimposed signs or billboards quickly pass by - San Francisco Trucking, The Grand Theatre - The Four Cohans in The Professor's Wife]
Young George: (asking at a desk) Any mail for Mr. Cohan?
Clerk: Oh, no. Your father picked up his mail.
Young George: I mean for Mr. George M. Cohan.
George (Cagney's voice-over): The next ten years rushed by like a circus train. Dad seemed content with the sticks, but I was straining at the leash.
Another clerk: Here's your mail, Mr. Cohan.
George (grown-up Cagney at age 23): Thanks. A couple of tickets for the show. (The tickets are to Robinson's Theatre, in Buffalo, NY, with The Four Cohans in "Four of a Kind.")
George (Cagney's voice-over): We were playing stock in Buffalo. And being versatile, I was playing my mother's father.

In 'Four of a Kind' opposite his mother (who is playing his daughter), George plays the part of an elderly gentleman with white hair, a cane, and a beard. In the audience is an attractive, prim woman dressed in her Sunday best who sniffles into her handkerchief. In a quavering, feeble voice of wisdom, George delivers the last line of the play's dialogue: "The road to happiness is paved with heartaches and stones."

In a memorable, charming sequence in his backstage dressing room while still dressed in the costume and makeup of the old man, "one of those stagestruck kids" is ushered in to talk to him following the show - she is the same young lady seen in the audience. The aspiring actress (and soon-to-be high school graduate) timidly, nervously and breathlessly blurts out:

Mary: I'm eighteen - I sing and I dance and I'm going to New York. Should I? (George reacts with puzzlement) Oh, Mr. Cohan, you're so old and so experienced in the theater, so fatherly. (He reacts with a gruff, drawn-out cough) Do you think it's wise? I mean - my being eighteen, singing and dancing, going to New York?
George: (in a fatherly tone) Well, that's very wise, I mean, being eighteen is very wise. And as for New York, the Four Cohans open there this fall with their new show with a new Cyclorama and two carloads of scenery.

Mary is utterly horrified when a seventeen year-old female performer ("a pipperino") in the show reminds George of their romantic date later that evening - "Roller-skating on a night like this? Why, there's a moon out? I'll be ready in five minutes." Still wishing to impress the old gent, the completely gullible girl auditions with a buck-and-wing dance. George finishes his deceptive con by exuberantly performing his own energetic buck-and-wing dance - a much more rousing, springy dance than hers. "I'm always as young as the people I'm with. And you've made me feel very young...(He clucks his teeth and tongue at her to make a funny noise)...very." Then, while proposing to take her to see managers to jump-start her career of acting and singing, he strips off his 80 year-old disguise of eyebrows and whiskers. George invites Mary out for "a nice cold bottle and a bird...That's what we in show-business call a piece o' pie and a glass o' milk." When he removes his gray toupee/hair piece, the last vestige of his makeup, she shrieks. He stomps on it as if it were flaming with fire.

The next scene dissolves into another poster bill - this time at O'Rourke's Varietie's, which is presenting a "Special Election Day Matinee" of The Four Cohans in Songs and Dances. On stage in matching tuxes and black dresses, the Four Cohans (Jeanne Cagney as Josie) sing and dance I Was Born in Virginia. Garbed in her own outfit, Mary watches from the wings of the stage as they finish to uproarious applause. At the end of the performance, George delivers his trademark curtain speech, thanking the audience on behalf of his entire family as each member of his family responds with a bow or curtsy:

Ladies and gentlemen. My mother thanks you. My father thanks you. My sister thanks you. And I thank you.

After finishing his part of the show, he encourages Mary, the "Dixie Nightingale," to sing confidently - he has promoted her career and expects her to be successful with his own material, even though she is, unannounced, switching songs by substituting his song (The Warmest Baby in the Bunch) for one that she rehearsed all week (The Wedding of the Lily and the Rose) for the stage manager:

George: What are you worried about? You're doing a George M. Cohan lyric to a George M. Cohan melody!
Mary: Yes, but it's my voice.
George: George M. Cohan discovered it. Nobody ever had a better start. Here's your introduction. Go on.

While negotiating a new offer with George's parents for "ten consecutive weeks in New York," the stage manager (William B. Davidson) realizes that the song Mary is singing hasn't been approved and that young George is behind the switch. The curtain is prematurely brought down on Mary, and George is furious: "You get that curtain up! You can't ring down on a George M. Cohan song!" When it dawns on the manager that it's George's song, he fires Mary ("...you'll not be singin' songs like that in my theater. Now you take a little tip from me, you start packing"), and then he blacklists George after being kicked and sent sprawling into the stage's backdrop:

Listen, squirt. Any more interference on your part and you'll be blacklisted in show business. You won't even be able to get into a stage door of any theater in this country. And once more, as for those songs of yours, they won't even be played on a hurdy-gurdy. (Mary leaves in tears)...Cohan, you're fired. You're cancelled, you're washed-up. You and your whole family.

The film proceeds to show George's early days of struggle as a young Irish song writer, singer and playwright:

George (in voice-over): Oh, things were tough. But at least I was in New York. I had a trunk full of songs and playscripts and a heart full of confidence. I'm glad I had it.
Publisher: (At Maurice Ruppe & Co., Music Publishers) I'm sorry, I can't use this, Cohan.
George: Youth needs confidence. I'd learned my job the hard way, all over the United States. And now guys who had never been past the corner cigar store were saying my stuff was no good. A kid had to believe in himself to buck that.

After being turned down at numerous music publishers along New York's Tin Pan Alley, George visits the Dietz and Goff Theatrical Enterprises offices. The walls are adorned with framed photographs of successful actors and actresses. To the jaunty tune of a piano during their audition, the self-assured George (with Mary) performs his own tune Harrigan (a song in their play Little Johnny Jones!) for Harold Goff (Chester Clute) and Dietz (George Tobias), two typical Broadway showmen. The song expresses pride in having Irish blood:

Harrigan

Verse
Who is the man who will spend or will even lend?
Harrigan! That's me!
Who is your friend, when you find that you need a friend?
Harrigan! That's me!
I'm just as proud of my [pronounced me] name, you see
As an Emperor, Czar, or a King could be.
Who is the man helps a man ev'ry time he can?
Harrigan! That's me!

Chorus Refrain
H - A - double R - I, G - A - N spells Harrigan
Proud of all the Irish blood that's in me,
And divil a man can say a word agin me.
H - A - double R - I, G - A - N you see,
Is a name that a shame never has been connected with,
Harrigan! That's me!

[In actuality, Harrigan was written in 1907 for use in Cohan's 1908 show/play Fifty Miles From Boston, a few years after Little Johnny Jones (the show, Cohan's third musical and his first hit, opened in November of 1904 and featured a song list including Yankee Doodle Boy and Give My Regards to Broadway). Little Johnny Jones was later filmed twice, as a 1923 silent and as an early sound musical in 1929.]

They are coldly told that the song doesn't sound appealing - and turned down. Sam Harris, another prospective writer/showman of a melodrama titled Wildfire witnesses George as he bursts out of the offices and makes a dire threat at the dour-faced agents:

You don't know it, boys, but your days are numbered. You're making room for the likes of me. And someday, Mr. Senior Partner, you're gonna come to me and admit you were wrong.

Always optimistic, George encourages Mary, who is struggling to stifle her sobbing, to keep her hopes high:

George: Come on now, Mary. Don't let a couple o' gilpins like that get under your skin. There's no sense in crying now.
Mary: Buffalo is such a beautiful city.
George: Is that what you're crying about?
Mary: (crying) It's a beautiful city, but I hate to go back to it.
George: Don't worry, you won't have to. I'll show them yet. I'm gonna have my name posted and plastered up and down Broadway until I'm as well known as Hood's Sasparilla. And if you'll stick along, we'll whip 'em to a standstill. We'll take 'em like Grant took Richmond.
Mary: I never really thought of leaving, George.
George: We'll make this whole theatrical business sit up and holler for help. That's what we'll do. They'll all hear from us. Every one of 'em. They'll all hear from us!

Sam Harris is also thrown out of the office - with his script.

At Madame Bartholdi's Boarding House, where "Special Weekly Rates to the Theatrical Profession" are offered, the place at the table where the Cohan family members sit is termed "Starvation Corner" by Fanny, the waitress. The Cohan's fellow boarders consider black-balled George as the problem-child in the family: "Everybody knows that you and Nellie and Josie can get work anytime anyplace, but nobody wants Georgie...Sure, he's made trouble in every theater this side of San Francisco." Having just entered into the boarding house hallway, George overhears and listens somberly to the discussion about their perceptions of him as a failure. His mother Nellie defends her son and the sanctity of their family:

His family hasn't black-balled him. We may have to take a lot of hard knocks and make a lot of sacrifices, but if they want our act they'll have to take him too. We're not breaking up our act or our family.

Concocting a story that his play Little Johnny Jones! has been bought by Dietz and Goff and will be in rehearsals for a few months, George suggests to his father that the family split up while he sets out solo and remains in New York: "Why don't you and Mom and Josie take whatever offers in the meantime to fill in?" His sister regrets breaking up: "But it won't be the same going back on the road without you, Georgie. Why, we'll be like a carriage with only three wheels."

Later, at Jack's Grill, Sam Harris is failing in his effort to sell his action-oriented, dramatic manuscript to Schwab (S.Z. Sakall), a wealthy Hungarian businessman and arts patron who is disinterested. He states that he prefers musical comedy instead:

I won't be in the theater to find out. I will be down the street watching a musical comedy. Before I put ten thousand dollars into a show, it must have songs, dances, and a lot of girls. Women, women. Little rose petals!

Overhearing their conversation, George inveigles his way into the discussion and promptly has the naive potential backer believing that he is on the verge of selling a musical ("with twenty ponies and twenty showgirls") to Dietz and Goff. Sparking Schwab's curiosity, George claims he has a song lyric called Yankee Doodle that he will sing and play on a piano in a private room of the bar:

Yankee Doodle

I'm a Yankee Doodle Dandy, A Yankee Doodle do or die,
A real live nephew of my Uncle Sam, Born on the Fourth of July!
I've got a Yankee Doodle sweetheart, She's my Yankee Doodle joy.
Yankee Doodle came to London, Just to ride the ponies.
I AM THAT YANKEE DOODLE BOY!

Schwab is convinced that he must back their musical (with Cohan and Harris as partners) or lose the deal for the musical to Dietz and Goff: "I'll give you a check to bind the deal." They have successfully persuaded him to back their production of Little Johnny Jones.

A hand opens the conductor's score (on a musical stand) for Geo M. Cohan's "Little Johnny Jones" - "The YANKEE DOODLE BOY". Now a theatrical musical performance within a flashback, the camera pans up to the stage - a race-track area - where beautiful chorus girls stroll with white parasols and well-dressed gentlemen bet on horses. George, as horse jockey Johnny Jones - the Yankee Doodle Boy himself, stands on a pedestal next to a race horse, and is soon surrounded by the long-gowned, glittering dancers/singers. He sings the film's classic, all-time favorite title song:

Yankee Doodle Dandy (Boy)

...I'm a Yankee Doodle Dandy, A Yankee Doodle, do or die;
A real live nephew of my Uncle Sam, Born on the Fourth of July!
I've got a Yankee Doodle sweetheart, She's my Yankee Doodle joy.
Yankee Doodle came to London, Just to ride the ponies,
I am that Yankee Doodle Boy.

As the rousing chorus is sung, the limber song and dance man George struts across the stage with a stiff-legged gait, bent forward with a straight upper torso. His high, straight-toed kicks, jerky convolutions, a bit of bouncing, twirling, tap-dancing, and other assorted movements make the dynamic, vigorous dance number come alive. He even uses stage walls as part of the dance floor. [The stiff-legged gait and the trick of running up the side of the stage wall were both true characteristics of Cohan's dance style.]

CHORUS
He's a Yankee Doodle Dandy, A Yankee Doodle, do or die;
A real live nephew of his Uncle Sam, Born on the Fourth of July.
He's got a Yankee Doodle sweetheart, She's his Yankee Doodle joy.
Yankee Doodle came to London, Just to ride the ponies,
He is that Yankee Doodle Boy.

At the conclusion of the jaunty number, the favored but "dishonest" 'Johnny' loses the Derby horse race and is "suspended for throwing the race."

The show is a smash hit - backstage between the first and second act, both Schwab and Sam are elated with George: "Oh, it's goin' wonderful, George, you've got 'em eatin' right out of your hand...You got a smash hit. It's in the air, kid, it's in the air. You can't stop anything that's in the air."

The next act in the musical is a night scene on the pier alongside a ship which is ready to sail from Londontown to "the city of old New York." Chorus members, who are both on the deck of the ship and on the pier, sing: All Aboard for Old Broadway. A gangplank connects the pier to the deck of the ship. As the boat is set to depart, George (as Johnny Jones) is told by another actor at center stage on the pier:

Watch for the skyrocket. If it goes off, you'll know that I've obtained certain papers from Anstey's cabin that will prove you innocent of throwing the English Derby. It'll mean complete vindication. So stick here on the pier and watch for the skyrocket.

At the top of the gangplank, the departing, New York-bound chorus member (Mary) expresses her faith in Johnny: "...don't worry. We still believe in you." Back on the pier, Johnny turns, looks and points toward Mary up on the deck, and sings another all-time classic tune:

Give My Regards to Broadway

Give my regards to Broadway, Remember me to Herald Square,
Tell all the gang at Forty-Second Street, That I will soon be there
Whisper of how I'm yearning, To mingle with that old time throng;
Give my regards to old Broadway, And say that I'll be there 'ere long.

The chorus on the deck of the ship reprises the lyrics back to him as the ship begins to move away from the pier. The pier darkens, and Johnny Jones is left alone to ponder his unknown fate. The ship, with tiny lights sparkling, doubles back in the distance, moving through the moon-lit night on the open water behind him. Suddenly, a skyrocket zooms up from the distant ship and explodes, showering the sky with a brilliant, bursting display of fiery sparks. Relieved that he is innocent, Johnny tap dances with his characteristically straight-legged movements under a spotlight.

As the curtain falls, the music swells and the audience applauds enthusiastically - all except agents Dietz and Goff who are standing in the back of the theater. Dietz smashes Goff's black top hat onto his head: "That was your department."