Plot
Thousands of years ago, a tribe of Minions, different from the one that would go on to serve Gru, are on a hunt to serve the world's greatest villains but inadvertently kill their masters in various ways. James, an artistic Minion with a passion for storytelling and drawing, quickly develops a close friendship with two others: Henry, a two-eyed minion who enthusiastically supports James, and Ed, a mute minion who communicates using sign language and becomes close to them. Among the many masters the Minions serve is a Russian warlock who is killed by a monster after Henry summons it from his spell book, which Ed then takes along with them.
Eventually, the tribe stumbles across a bank robbery and decides to chase after the robber to become his henchmen. However, the robber is revealed to be an actor, filming a chase scene for a 1927 Hollywood movie. Though filmmaker Max is furious with the Minions, studio executives Frank and Elwood Bright are enamored by their antics. Max hires the Minions to star in his films and soon become a global phenomenon, appearing in several silent films and living a glamorous life of Hollywood stardom.
When sound film is introduced, the Minions are unable to adapt to the new technology due to their incomprehensible language. Costing the studio millions in failed material, the Minions are fired and forced to rest in an abandoned factory. Not wanting to give up on his passion for storytelling, James comes up with an idea to make his own movie titled Minions & Monsters, where the Minions would fight against giant monsters. The leader of the tribe, Dick, rejects James' idea and leads the rest of the Minions back towards finding a new evil master, but Henry and Ed break away from them to help James make his film a reality. They pitch it to Max, who encourages James to work on the movie, providing him with a film camera. To help James bring his film to fruition, Ed uses the warlock's old spell book to summon a squid monster for the movie. In doing so, the trio releases a small, green monster named Gary Orkam Oliver Magma Ichabod "Goomi" the Deceiver who offers to help him find the perfect monsters for his film, leading them to a frozen fortress and frees sea monsters Howard and Phillips under the false pretense of using them as stars in James' movie. In reality, he aims to use them to summon Irene (Eyereen), a large, orange, multi-eyed blob monster, in order to destroy the world and get revenge.
Meanwhile, Dick and the other Minions are hired by Dort, apparently a man who claims to be an alien robot on a mission to invade Earth. While beginning his quest for world domination, Dort falls in love with women's rights activist Debbie, enlisting the Minions' help to romantically pursue her. While James and his crew begin production on his movie, Henry overhears Goomi's plan to Howard and Phillip and tries to alert James, but only for the monsters to kidnap him and convince James to use him as a sacrifice in filming the scene where Irene will be summoned. Just as filming begins, Goomi and the monsters conjures Irene, and she begins wreaking havoc, chasing Henry through the streets in the process.
When Dort and the other Minions witness Irene during his date with Debbie, Dort seemingly flees, leaving the Minions to fend for themselves. Irene succeeds in swallowing Henry, and James drives a milk car through her to rescue him. The Minions try to destroy Irene, but to no avail. As she closes in on them, Dort reappears with Dick and the other Minions in spacecraft, showing his true identity as an alien robot, and they successfully destroy Irene. Henry and James cast an undo spell to send Goomi, Howard, and Phillips back with the spell book. The public hails the Minions and Dort as heroes. Ed has captured the entire battle on film, allowing the Minions to complete James' movie. Months later, Minions & Monsters debuts in theaters and receives a standing ovation from the audience while Dort starts a family with Debbie.
In a film museum, tour guide Olivia, who tells the story of James and Henry, finishes her story before it is revealed that the entire plot, including the tour, is a film within a film directed by James and Henry. In the mid-credits, the spell book falls into the hands of Gru's Minions and is tested by James, Henry, Kevin, Stuart, and Bob, as well as one of Gru's adoptive daughters, Agnes.