Convicted of manslaughter for beating a man to death while defending a woman, hot-tempered Vince Everrett is sentenced to up to ten years in the state penitentiary. His cellmate Hunk Houghton, is a grumpy old-timer who runs a prison racket using cigarettes as currency. On days when the inmates’ harsh living conditions breed animosity among the men, Hunk sings ballads on his guitar to calm them. After Vince shows interest in his musical skill, Hunk, an old country-western singer, helps the young man master the chords and rhythm. One day, the warden assigns Hunk to produce a nationally televised prison talent show to divert the attention of the state investigators visiting the prison. Hunk showcases Vince, whose performance inspires thousands of young viewers around the country to send letters to the prison. Surmising that Vince's appeal will lead to success upon his release from prison, Hunk pays off the mailroom clerks to keep the fan mail a secret and offers Vince a contract, which makes Hunk his manager and divides the profits 50/50 between them. Days later, Vince receives a flogging for getting into a brawl, but Hunk shows little sympathy and advises him to “do unto others as they would do unto you, but do it first.” When Vince's release date arrives, the warden hands him fifty-four dollars and, to Vince’s surprise, a large sack of fan mail. After taking a room at run-down hotel, Vince buys a guitar from a pawnshop and goes to club owner Sam Brewster, a friend of Hunk's, to ask for a job. When Sam offers him work as a busboy, Vince boldly performs a number without Sam’s permission. Although the patrons show little interest, Peggy Van Alden, who works in the exploitation division of a record company, becomes smitten with Vince and suggests that he record the song at a studio session to improve it. Days later at the studio, after a mediocre recording, Peggy encourages Vince to try the song again but “with a little fire.” Excited by the second recording, Peggy asks Geneva Records executive Jack Lease to release the song, and although Jack suggests the song is too experimental, he asks to keep the recording for the evening. When Peggy later secures a contract with a smaller label, a sullen Vince refuses to celebrate until he reaps some of the profit from his efforts. Wanting to introduce Vince to her father, a professor, and mother, Peggy takes Vince to her parents’ house for a party, but when the academic crowd tries to engage the young musician in a conversation about progressive jazz, insecure Vince insults her parents and leaves. As Peggy argues that his conduct is unforgivable, Vince’s kisses break her resolve. Days later, Peggy and Vince learn that Jack has recorded Vince's song using popular singer Mickey Alba and stolen Vince's arrangement. Undeterred, Vince suggests to Peggy that they start their own record label, Laurel Recordings, in which Vince will record his songs while Peggy promotes and distributes the product. Peggy agrees to a forty percent cut of the company’s profits; however, she is soon frustrated with Vince’s myopic drive for money and his lack of interest in furthering their romantic relationship. Finding it difficult to secure any airtime for Vince's first album, Peggy asks old friend and disc jockey Teddy Talbot to play a single from it. When the song is a smash hit, Vince quickly becomes a successful performer and playboy. One night, Peggy visits Vince at one of his many lavish parties and catches him kissing singer Laury Jackson. Peggy then brusquely agrees that their relationship should remain solely business and leaves. Soon after, Hunk, just released from prison, asks his old friend for a spot on an upcoming television show and Vince reluctantly consents. At the television recording, Vince sings the catchy "Jailhouse Rock" accompanied by dancers in prison fatigues, but Hunk’s old-fashioned country number is cut from the show. Vince's cold response to his friend’s disappointment prompts Hunk to pressure Vince with the contract written in prison. Reminding Hunk of his dishonorable scheme to hide the fan mail and then rob Vince of his profits, Vince instead offers Hunk ten percent in exchange for being his lackey. Soon after, Vince signs a contract to star in a Hollywood movie with actress Sherry Wilson. The established leading lady is not amused with Vince's common ruffian interests, but during their first love scene rehearsal, Vince's powerful kiss melts her and a romance develops. Days later at a party, after Vince sings a number about loving Sherry despite her "square" ways, then he tells Peggy about a profitable offer from Geneva Records to buy out Laurel Records. Vince’s greed and disregard for the company they built together leads Peggy to flee the party. Later, Vince orders Hunk to complete another menial task, humiliating his friend. When Peggy arrives at the apartment to discuss business, Vince’s thoughtlessness drives her to tears and causes a now drunk Hunk to take several punches at the star, accidentally hitting Vince's throat. After an emergency tracheotomy at the hospital, Vince is forced to recuperate in silence for several weeks, unsure of whether he will sing again. Weeks later, a healed Vince is scared of singing again, but with the support of his loyal friend Hunk and Peggy's love, he attempts an enchanting ballad for Peggy and discovers his unique voice is still intact.