Act One

A strange and fantastic red-and-white-striped top hat appears on an empty stage, full of possibilities. A Boy enters and is drawn toward the magical hat. The Cat in the Hat suddenly materializes. "I can see that you've got quite a mind for your age," quips the Cat as he/she begins singing about the power of imagination ("Oh, the Thinks You Can Think"). Throughout the song, famous characters are introduced who will figure in the musical: Horton the Elephant; Gertrude McFuzz, the bird with the one-feather tail; the Whos of Whoville, including the Mayor and his Wife; General Genghis Khan Schmitz; Mayzie La Bird; the Sour Kangaroo and the Citizens of the Jungle of Nool. As the energizing opening number comes to a close, the Boy and the Cat use their imaginations to transport everyone to the Jungle of Nool, and the adventures begin.

Horton is splashing in a pool when he hears a distant cry for help. ("Horton Hears a Who"). He follows the sound to a tiny speck of dust floating through the air and realizes that there are people living here, people so small that they can't be seen: the tiny citizens of Whoville. Horton vows to help them and places Whoville safely onto a soft clover just as Sour Kangaroo and her baby arrive. The Sour Kangaroo thinks Horton is crazy for talking to a speck of dust, and she and the rest of the Jungle Citizens mock him for his delusions. ("Biggest Blame Fool"). The rascally Wickersham Brothers, a cool group of bad-boy monkeys, join in the fun of teasing Horton. The Cat in the Hat weaves through the number, taking on the persona of a talk show host who interviews everyone in the jungle, including Mayzie La Bird and her backup group of Bird Girls. The one person who stands up for Horton is his neighbor, Gertrude McFuzz, who is not noticed by anyone, most of all Horton.

Horton is left alone and discovers much more about the Whos and their tiny town of Whoville ("Here on Who"). He assures them of his belief that "a person's a person no matter how small." The Cat in the Hat, who is continuously present, throws the Boy into the story, and he becomes JoJo, son to Mr. and Mrs. Mayor of Whoville. They are both very unhappy with Jojo because his "Thinks" have gotten him into trouble at school.

Jojo is scolded and told to "take your bath and go to bed," but the Cat in the Hat has another idea... and Jojo's imagination gets the better of him again. ("Oh, the Thinks You Can Think – Reprise") Magically, his bathtub becomes McEligott's Pool, full of fantastical fish ("It's Possible")! The fun is interrupted when Mr. and Mrs. Mayor rush in – Jojo has flooded the house with bathwater. With Jojo finally in bed, his parents lament the change in him since his "Thinks" began ("How to Raise a Child"). The Cat in the Hat gives them an idea to help solve Jojo's problem.

The next morning, Mr. and Mrs. Mayor introduce their son to General Genghis Khan Schmitz ("The Military"). They feel the rigors of military school will straighten out their unusual son.

After a long and very tough first day at military school, Jojo sits alone in his bunk. Simultaneously, Horton sits alone guarding the clover ("Alone in the Universe"). Horton and Jojo hear each other and become friends when they realize that their imaginations are so much alike – "one true friend in the universe who believes in me."

In another part of the jungle, Gertrude has just written her 437th love song about Horton ("The One Feather Tail of Miss Gertrude McFuzz"). She believes that Horton doesn't notice her because of her pathetically small and uninteresting tail. Mayzie appears with her Bird Girls and offers advice ("Amayzing Mayzie"). This leads Gertrude to Doctor Dake (played by the Cat in the Hat) and his pills for "amayzing" feathers. After taking too many pills, Gertrude is very happy as her tail begins to grow ("Amayzing Gertrude"), but the Cat in the Hat warns that trouble is brewing.

The Wickersham Brothers are up to no good ("Monkey Around") and they decide to steal the clover with Whoville on it. They ambush Horton, grab the clover... and "Chasing the Whos" begins as the monkeys tease Horton and he huffs and puffs after them, all over the Jungle of Nool. The Cat in the Hat plays a helicopter newscaster, tracking the chase.

The Wickershams hand off the clover to "a black-bottomed eagle named Vlad Vladikoff," who flies off with the clover and drops it. As the clover plummets toward the ground, the Cat in the Hat freezes the action for a blithe, ironic song ("How Lucky You Are"). The Cat unfreezes the action, and the Whos drop directly into an enormous field of clover.

Horton begins looking for the Whos, clover by clover by clover. Gertrude has followed the chase and arrives with her now incredibly long and unwieldy tail, determined to tell Horton how she truly feels ("Notice Me, Horton"). But Horton doesn't notice her at all and just continues looking for the Whos. Gertrude leaves, rejected and sad.

Mayzie La Bird calls to him from her nest in a tree. She's bored to death ("How Lucky You Are – Reprise") and she convinces Horton to sit on the nest for her while she takes a brief vacation ("Horton Sits on the Egg").

Seasons pass, and Horton is still stuck, sitting on the egg, the Whos are still lost in the clover, and Gertrude still cannot get Horton to notice her or her very long tail. Hunters suddenly arrive and capture Horton and the egg. Gertrude is unable to help because her tail is so large that she can no longer fly. Chaos begins but, once again, the Cat freezes the tableau and Horton, Gertrude, the Cat and all the Whos send the audience out to intermission ("How Lucky You Are – Second Reprise"). Just before doom strikes, the curtain comes down.

Act Two

As the orchestra tunes up, we realize that the conductor is the Cat in the Hat. The music becomes increasingly wild and out of control – pages fly, the baton goes crazy, the Cat does his/her tricks and finally regains control so that Act Two can start. ("Seussical Entr'Acte").

The Boy questions the Cat about the future of Horton, the egg and JoJo, but the Cat just sends the Boy back into the story as Jojo, and we segue to three little scenes, reprising Act One: Horton is still surrounded by hunters as he sits on Mayzie's egg; although the tiny town of Whoville was damaged in the "fall," the military school continues to march. Jojo marches, wondering what the point of marching is when their world is in ruins. Back in the jungle, Gertrude is extremely worried about Horton, but can hardly walk without help because her tail is so long and heavy.

Now the action begins, as Horton, still on the tree nest, is carried away by the hunters ("Egg, Nest and Tree"). After a long, arduous journey, Horton arrives in New York, where he is auctioned off to the circus. The "Seusseby's auctioneer" is played by the Cat, who allows the audience to bid on Horton.

The Cat then plays Mr. McGurkus and introduces us to his fantastical circus, with Horton as his main attraction ("The Circus McGurkus"). As the circus travels across the country, Horton worries about Jojo and Whoville, wondering when Mayzie will return to her egg; ("The Circus on Tour / How Lucky You Are – Reprise").

The circus lands in Palm Beach, where we find Mayzie under a palm tree, bemoaning the monotony of vacationing ("Mayzie in Palm Beach"). She decides that she needs a change of scenery and heads to the circus, where she runs into Horton.

He begs her to take back her egg, but Mayzie decides that Horton would be a better parent for her egg than she could ever be ("Amayzing Horton"), so she gives him the egg for good and leaves before he can say no. Horton accepts the responsibility of caring for the egg ("Alone in the Universe – Reprise"), even though he worries about JoJo and the Whos. He sings the egg a lullaby ("Solla Sollew") that is echoed by JoJo and Mr. and Mrs. Mayor.

The next morning, General Schmitz and his military cadets head off to war to fight the "Butter Side Downers," who eat their bread the wrong way ("Green Eggs and Ham II"). JoJo confronts the General about the ridiculousness of the war and quits, marching off in the direction of a minefield. We hear an extremely loud explosion, and Jojo is gone.

Back in Whoville, the Christmas pageant is under way, led by the Grinch ("The Whos' Christmas Pageant"). General Schmitz suddenly enters with his cadets and approaches Mr. and Mrs. Mayor with horrible news ("A Message from the Front / Solla Sollew – Reprise"). JoJo has been lost in the war, a war which has become questionable in everyone's eyes.

The Cat helps us discover that Jojo has survived, but is confused and lost ("Alone in the Universe"). Frightened, Jojo blames the Cat for all his troubles. The Cat helps him find his way home to the arms of his parents by listening to his own hunches. ("Havin' a Hunch").

Far away, at the circus, Gertrude finally finds Horton, asleep in his cage. She has gotten rid of her unwieldy tail and has journeyed great distances and through much peril ("All for You") to find and rescue him. At the end of her number, she mentions one more thing: she also has found the Whos' clover! Horton finally notices that Gertrude is amazing.

But just as Horton finds the Whos again, the Sour Kangaroo and the Wickersham Brothers arrive and make a citizen's arrest . They take Horton back to the Jungle of Nool, where he is put on trial, "for talking to a speck and sitting on an egg." The trial begins ("The People versus Horton the Elephant"). Judge Yertle the Turtle sentences Horton to the Nool Asylum for the Criminally Insane, sentencing the speck of dust to be boiled in oil. Horton trumpets his protest and tells the Whos that they must yell to be heard; they have to prove they exist... and there's no time to lose!

The Whos scream and make as much noise as they can, but, still, only Horton can hear them. Suddenly, Jojo comes up with a Think: a new word to shout that will be heard by everyone: YOPP! At the last minute, all of the animals of Nool hear Jojo's cry, and Whoville is saved. Just then, the egg begins to crack – all gather around as the new baby emerges – and they are astonished to see that it's... an Elephant Bird! Horton looks to Gertrude for help, realizing that she is his "one true friend in the universe," and she agrees: "You teach him earth and I will teach him sky." A new and very unusual family is formed.

As the show ends and all are united, the Cat hints that many more adventures are likely to occur "if you open your mind, oh, the thinks you will find" ("Oh, the Thinks You Can Think – Reprise"). All the characters vanish, leaving The Boy alone onstage with the red-and-white-striped hat, which embodies his limitless imagination. As he puts it on, it falls over his eyes, putting the stage into BLACKOUT!