The story begins as a fierce storm begins to rage in the sky, the narrator boldly proclaiming that a delivery man will cut his way through the danger no matter what...the Delivery Stork that is. A whole flock of them are flying towards the WDP Circus Winter Headquarters in Florida to drop off the latest batch of baby animals for the troupe. Everyone from the tigers to the hippos happily receive their newborns—all except Mrs. Jumbo, one of the circus elephants. As the storks drop off each of their packages, her new baby never arrives, leaving the elephant saddened as the circus is due out tomorrow morning for the start of the season.
The next morning, a whistle is heard as Casey Jr., the circus's sentient steam locomotive, is preparing to depart. Every abled body from man to animal is helping to load the train to get ready for the tour. As the elephants load into their stock car, Mrs. Jumbo takes pause to see if the stork is bringing her baby, only for the Elephant Matriarch to hurry her up into the train. Within moments, said matriarch is stuck, but just as quickly as they get her unstuck and onboard, the Ringmaster ushers Casey to begin. One bumpy start later, and the train is off, huffing through the countryside as a chorus utters that Casey is back out on the line and on the move with the circus. Overhead, Mr. Stork finally arrives with the baby elephant, taking note of the moving train and being ushered into the stock car by the other elephants. A traditionalist as ever, Mr. Stork goes through the rigamarole to drop off the baby (soon named Jumbo Jr.) by procedure, only to get snagged on a mail hook in the middle of his cadenza. The other elephants soon gawk over the newly arrived Jumbo Jr., until he sneezes and reveals he has rather large ears. Caddy, Prissy, and Missy dub him "Dumbo" over his large ears, but Mrs. Jumbo shuts their stall and cuddles her newborn.
Late in the evening, after conquering a mighty hill, Casey arrives in town with the circus and stops with a thunderous screech. The troupe then begins unloading in spite of a storm, with the roustabouts and the elephants setting up the big top in preparation for the next morning. Come sunrise, the town is alight with festivities as the Ringmaster leads a parade. Poor little Dumbo trips during his debut, for which he is roundly mocked. Once everyone gets back to the tent, Mrs. Jumbo gives him a bath, then plays a little hide-and-seek. Unfortunately, the fun stops when the circus lets the guests in, and a bratty kid named Smitty starts making fun of Dumbo. When he tries grabbing him, Mrs. Jumbo snaps up the little brat and spanks him. Assuming she's gone mad, the Ringmaster and the handlers narrowly manage to trap her, locking her up in solitary confinement and leaving poor Dumbo alone. With news of this tirade reaching the other elephants fast, they further disavow Dumbo and ignore him entirely. Luckily for Dumbo, a mouse named Timothy takes pity on his plight and gives those pesky pachyderms a good scare—a little too well, as he frightens Dumbo in the process. Luckily, he's able to convince the elephant he's on his side by proclaiming he will help to free Mrs. Jumbo from her prison. All they got to do is build an act; make him a star! Dumbo the Great!
But the Great what? As the two ponder, Timothy hears the Ringmaster babbling about wanting to have the other elephants build a pyramid, but can't think of a climax. The little mouse takes advantage of this to put the idea in the Ringmaster's head that Dumbo should be the climax. Sure enough, during the next show, the pyramid is made (at the great expense of the other elephants), but Dumbo's ears trip him up in spite of Timothy's best efforts to keep them tied up. Within moments, the pyramid collapses, bringing the big top down with it. Forced to move on, Casey and the circus train solemnly heads to the next stop as the other elephants lick their wounds. Even worse for poor Dumbo, he's been made a clown as punishment! Fully disavowed by the rest of the elephants, Dumbo is made to perform a humiliating jump dressed in full baby garb. Left crying, Dumbo is at his lowest point by the end of the act. Timothy takes Dumbo to see his mother, but the bars still separate them as the little elephant is forced to bid her goodbye after their short visit. Meanwhile, the clowns celebrate their night's success by going to hit the big boss with the idea to raise the platform Dumbo jumps off by several hundred feet (and a raise for themselves), unknowingly dropping a bottle of wine into a water pail. Dumbo takes a big drink from it to help cure a case of the hiccups, getting him (and soon Timothy) drunk in the process. Both then experience the nightmare of a horde of pink elephants appearing before their eyes.
The next morning, a flock of crows—Dandy, Deacon, Fats, Dopey, and Glasses—spot the hungover elephant and mouse and quickly take to mocking them. As Timothy tries to get them to back off, Dandy points out they're laughing because the two are in a tree! Moments later, they fall into a lake, and decide to head back to the circus. But how did they get up into that tree, Timothy wonders? They can't climb trees, nor can they jump—maybe they flew? They did fly! Dumbo's ears can help him fly! No sooner does this idea slip out of Timothy's mouth do the crows mock the idea. At that point, Timothy's had enough and digs into the quintet, pointing out how bad Dumbo's had it already. Realizing the error of their ways, the crows quickly offer to help Dumbo fly...through the use of a Magic Feather. One test flight later, and it works! Dumbo really can fly! The circus is gonna be in for a shock come tonight's act!
By evening, Dumbo is prepped at the peak of a tower, ready to surprise the audiences with his new gift. But just as he jumps, the feather slips through his trunk! He quickly panics as Timothy begs Dumbo to flap his ears before they hit the ground. And just like that, Dumbo narrowly avoids disaster and flies, shocking everyone in the audience to this miracle. With his newfound gift, Dumbo is quick to take revenge on the clowns, the Ringmaster, and the elephants that mocked him, and just as quickly does word of his gift spread across the world. His ears are insured for $1 million dollars, the US military makes a squad of bombers after him, and Timothy is able to secure a lucrative contract with the circus. His stardom secured, Dumbo joins his mother, now free from confinement, aboard his private observation car on the circus train as Casey happily puffs away, the other elephants now accepting of him, and the crows bidding him farewell.
