A small you-never-heard-of-it town somewhere in the Midwest
A twenty-four hour period, during the summer of 1955.
Somewhere in the midwest in the 1950's, Chad, a hip-swiveling, guitar-playing roustabout is being released from jail ("Jailhouse Rock"). The warden doesn't appreciate a guy like Chad ridin' into town, playin' his music and excitin' the locals. Chad rides off on his motorbike.
In a nearby dreary little town, Natalie, a young mechanic, is dreaming of love and adventure. She yearns for one true love to take her away, but she doesn't realize that her best friend Dennis has a secret crush on her. Sitting in Sylvia's, the local cafe, the whole town sings the blues ("Heartbreak Hotel"). Then the roar of a motorbike: it is Chad, riding into town. Chad is in need of a mechanic and he's introduced to Natalie, who is instantly smitten and promises to fix his bike.
Chad asks about any excitement in town, but he's told that excitement is outlawed under the Mayor's strict rules: no loud music, no indecent behavior. Chad, incensed, promises to breathe some life into this sad, little town and he touches a broken-down jukebox, and it immediately comes to life ("C'mon Everybody"). As Chad and Natalie go off to fix his bike, Mayor Matilda enters with Earl, the sheriff, and her son, Dean. Matilda scolds the citizens for dancing and singing, and then goes off to find the root of this newfound evil. As soon as she exits, Dean meets Lorraine, Sylvia's pretty younger sister, and the two share a nervous and flirtatious smile. Meanwhile, Natalie is working on Chad's motorbike. She tells him of her dreams of the open road, and he tells her that she must follow her heart ("Follow That Dream").
After Chad exits, Natalie, in an attempt to look more girly, puts on the only dress she owns -- a tattered old one she uses to clean car engines. Dennis runs into Natalie and he is about to tell her how he feels for her, when Chad enters and interrupts. Ignoring Natalie, Chad asks Dennis to become his sidekick and the overjoyed Dennis accepts. Suddenly, the beautiful and glamorous Sandra, the new girl in town, appears, and Chad is struck down with a case of love! Chad tries to smooth-talk her, but she resists ("Teddy Bear/Hound Dog").
Later that day, at Sylvia's Honky-Tonk Cafe, Jim and Sylvia speak about the strange behavior that seems to have befallen the town since Chad's arrival. Natalie enters in her greasy dress, and Lorraine has her change into one of her dresses -- it is clean and cute and Natalie looks lovely. She rushes off in pursuit of Chad.
Dean (the Mayor's son) meets Matilda at the bus stop, after a brief meeting earlier, and she tells him that she's sending him back to military school on the next bus. Lorraine enters, and Dean tells her the terrible news -- they're about to be separated. Hopelessly in love, Dean and Lorraine decide to run off together ("It's Now or Never").
Chad follows Sandra, but she will have nothing to do with him. Dennis meets Natalie on the street and shows off his new hunting cap, which makes him feel like "one of the guys." Natalie has a sudden inspiration and she grabs Dennis' hunting cap. Alone in the garage, she dresses as a leather-jacketed male roustabout.
As Chad bemoans Sandra's lack of attraction to him, Dennis comes up with an idea. He volunteers to take her a Shakespearean sonnet. Desperate, Chad agrees. But before Dennis leaves, a leather-jacketed roustabout rides into town ("Blue Suede Shoes"). It is Natalie, dressed as a fellah named Ed. Chad is excited by Ed's coolness and manliness and he asks Ed to be his new sidekick. Heartbroken, Dennis exits. Chad instructs Ed that his first job as his new sidekick is to give the sonnet to Miss. Sandra.
Ed arrives at the museum and gives Sandra the sonnet. Sandra is so moved by the sonnet that she finds herself drawn to this strange-looking young man.
As the sun goes down, Mayor Matilda is cracking down on the perceived immoral behavior that's running rampant through the town. She comes upon a boy and a girl holding hands, and she's stunned to see that it's her precious Dean with Lorraine. Dean, for the first time, disobeys his mother and shows her that he can now dance. He and Lorraine run off into the night. Matilda promises to throw Chad out of town for what he has done, and she and Sheriff Earl drive after Dean. Ed tells Chad that in order to avoid being kicked out of town, he should hide in the abandoned fairgrounds, searching for love. Dennis comes upon Natalie, who's still dressed as Ed, and Dennis reveals that he's upset about the way Chad treats her ("It Hurts Me"). Natalie insists that Chad is the only guy for her.
In an attempt to win Chad, Natalie gets an idea -- she convinces Chad to teach her (i.e. Ed) how to ask a girl out, but in the process, they experience a funny and uncomfortable moment. Sandra enters, looking for Ed. Left alone, Chad is about to hit Ed, but he realizes that he can't. Ed gives Chad some "alone time," and Chad realizes that he has feelings for his new sidekick.
In another part of the fairgrounds, Mayor Matilda enters, followed, as always, by the silent Sheriff Earl, and she vows to bring the roustabout down ("Devil in Disguise").
In another part of the grounds, Dean and Lorraine plan to catch the morning train out of town, but Chad convinces them and all the townsfolk to stay and fight for their love.
In the center of the fairgrounds, Matilda gathers the townspeople together to form a pious posse to both find her son and arrest Chad. But as Chad enters, as does Dean and Lorraine -- and the final confrontation ends with rousing "All Shook Up," and true love prevails!