In Belleville, New Jersey, 1961, the narrative kicks off with Tommy DeVito, portrayed by Vincent Piazza, who confidently asserts that he is the keeper of their story. He boldly claims that without his influence, he and his friends could have ended up in dire situations, such as being in someone's trunk with fatal consequences. He drops by the barbershop, where his friend Frankie Castelluccio, played by John Lloyd Young, is giving a shave to the notorious mobster Gyp DeCarlo, excellently depicted by Christopher Walken. Tommy's unexpected entrance causes Frankie to accidentally nick Gyp's cheek, but the mobster brushes it off, unfazed.
Once Tommy drops Gyp off, he heads to Frankie's home, where dinner with his parents is underway. Frankie's mother expresses her disapproval of his friends, signaling a troubled family dynamic. Undeterred, Tommy convinces Frankie that they are headed to practice for a school event, but instead, they plan a heist to steal a vault. When they try to force it into Frankie's car, they encounter trouble and end up crashing through a store window, making a hasty escape.
Later, the trio performs at a club as The Variety Trio. Tommy brings Frankie on stage to showcase his remarkable falsetto, catching the attention of a red-haired beauty in the audience. Backstage, Tommy offers some colorful advice about the two types of women— Type A and Type B. Unfortunately, Frankie’s attempt to win over the redhead leads to an encounter with the police due to their earlier mischief.
Frankie's following weeks are tumultuous as he, Tommy, and their friend Nicky face legal consequences for their antics, with Frankie's parents ultimately ordering Tommy to stay away. Sent to a correctional facility for six months, Tommy's return sparks chaos as he and Nicky create more trouble while attempting to break into a church with Frankie.
As time passes, the boys return to the club, and Frankie finds himself charmed by Mary Delgado, a captivating woman whose relationship adds new layers to his life. Despite Tommy’s warnings, Frankie pursues Mary fiercely, leading to their marriage soon after.
Frankie's life, however, is filled with tension when he finds himself driving with two unsavory characters, Stosh and Donnie, resulting in chaos and near-death experiences. Amidst the thrills, Tommy has a different vision to further their ambitions in music. He learns about a promising songwriter, Bob Gaudio, magnificently portrayed by Erich Bergen, whose sharp talent will change their futures.
As the band, now called The Four Lovers, faces numerous challenges, including a unique name and sound, they climb the ranks with Bob’s songwriting. Their big break arrives with hit songs like "Sherry," which catapult them into stardom and a lavish lifestyle—yet fame comes at a cost. Tensions bubble beneath the surface as Frankie's marriage suffers under the weight of the lifestyle brought on by touring, leading to heartache.
The unfolding drama intensifies as they face betrayal, love, and financial woes, particularly when Tommy's dealings with loan sharks complicate their success. As the pressure mounts, the group’s dynamics shift, causing cracks that threaten their bond. With a series of betrayals and reconciliations, the story climaxes in a poignant reunion at the Rock and Roll Hall of Fame in 1990, where Frankie, Bob, and Nick reflect on the path they've traveled together.
Ultimately, they resurrect their past by performing together once more, singing "Sherry" as each member of the group shares their thoughts on their journey. The film concludes with a nostalgic note, showcasing the enduring bond forged through music, friendship, and the trials they faced, presenting "December 1963 (Oh What A Night)" as a final celebratory anthem.
