The film kicks off during a tour at a movie studio where the enthusiastic tour guide, Olivia, unveils a fascinating array of props from iconic films such as E.T., The Matrix, and even features a cameo by George Lucas, who voices himself in a glass enclosure. Olivia goes on to explain that two Minions, James and Henry, played a crucial role in transforming Hollywood as we know it.
The narrative unfolds in the early 20th century, as the Minions are on a quest to find their evil master. Among them is James, a creative Minion with a penchant for storytelling, which unfortunately leaves him feeling like an outsider among his peers. Their journey takes them to an island where they encounter a giant cyclops. Here, James crafts a whimsical Lego-like stone painting that inadvertently causes chaos, leading the cyclops to kick the Minions out. Though the tribe is upset with James, he forms a strong bond with Henry, who finds him amusing, and Ed, a hearing-impaired Minion. They are guided by Dick, a leader not particularly favored by the others.
Their adventure continues when they end up working for a malevolent sorcerer. Ignoring his stern warnings, James and Henry meddle with the sorcerer’s spell book, successfully summoning a fluffy pink bunny creature that turns out to be far more menacing, wreaking havoc and ultimately reducing the sorcerer to ashes. Although they manage to send the creature back, they find themselves once again without a master.
As their travels progress, the trio stumbles upon what appears to be a bandit making off with stolen treasures. They pursue him, leading to a train hijacking that ends in a spectacular derailment through the streets of Los Angeles, only to discover that they were part of a movie set all along. The furious director, Max, orders the Minions off his set, but when he presents the footage to the studio executives, Elwood and Frank Bright, both voiced by Jeff Bridges, they perceive the Minions as a brilliant addition to the film. To Max's surprise, he is compelled to include them in further scenes, leading to hilariously chaotic battle sequences.
Following this unexpected success, the Minions become the talk of Hollywood, appearing in a succession of blockbuster films. However, their fortunes take a downturn as the advent of sound in cinema proves challenging for the Minions, whose unique language interferes with dialogue. As a consequence, the Brights are forced to let them go from the studio.
In a bid to reclaim their status, James devises an idea for a monster movie starring himself and the remaining Minions. Despite his enthusiasm, Max informs James that while he cannot assist, he admires the idea and wishes him well. Unfortunately, Dick chooses to leave with the other Minions to find a new leader, leaving James, Henry, and Ed to fend for themselves.
Determined to make his film a reality, the trio enlists the help of Goomi, a diminutive, Cthulhu-like monster they summon from the spell book. Goomi, grateful for his freedom, shares that he knows where to find authentic monsters for James’s project. This leads them to an island inhabited by monstrous creatures.
Meanwhile, Dick and the other Minions encounter an alien robot named Dort, who claims to be on a mission to enslave Earth. Intriguingly, he forms a relationship with a suffragette named Debbie during their escapades.
On the island, Goomi reunites with his monstrous friends, Phillips and Howard, who are gigantic kaiju. They accompany the Minions back to the studio as James prepares for production. However, Henry overhears Goomi's plan to unleash a fearsome monster named Irene as an act of vengeance against humanity, and after a brief chase, Henry is captured.
In a twist, Goomi proposes that they summoning Irene during the film's opening scene, with her “sacrificing” Henry as part of the act. When the enormous orange blob bursts forth, chaos ensues, and she begins obliterating the movie studio. Fortunately, Henry manages to escape, prompting a frantic chase involving James and Ed.
As Irene rampages through the town, the Minions, along with Debbie and Dort, witness her destruction. Dots leads a charge in spacecraft, armed with lasers that manage to neutralize Irene by turning her into a hardened mass that ultimately explodes. Following this triumphant showdown, James, with Ed's help, uses the spell book to return Goomi, Phillips, and Howard back to confinement.
Eventually hailed as heroes, the Minions bask in the glory of their success. Ed captures every laugh of the moment, enabling James to finalize his film, which premieres to great acclaim, leading him to receive a golden banana award— a playful nod to the Oscars.
As Olivia concludes the tale, it is revealed that the entire story was a creative endeavor by James and Henry, turning every character, including Goomi, into actors portraying their roles. During the credits, the Minions are seen amusing themselves with the spell book after being adopted by Gru, pulling pranks and causing delightful chaos, showcasing their forever playful spirit.
