Commander Magenta, CEO of Red Pharmaceuticals, seeks to revive the Red Ribbon Army that his father Commander Red led and was ultimately destroyed by Goku. Magenta and his assistant Staff Officer Carmine seek to recruit Dr. Gero's surviving grandson, Dr. Hedo, a superhero-obsessed mad scientist who was released from jail after serving a lengthy sentence for grave robbery. Hedo accepts the offer, despite his initial reservations, after Magenta convinces him that Capsule Corporation and the Z-Fighters are evil organizations. While Goku and Vegeta are training under Whis on Beerus' planet alongside Broly, who is being taught to control his power, Piccolo is annoyed over Gohan wasting his potential while training the latter's daughter Pan. Piccolo is then attacked by a Red Ribbon android named Gamma 2, but manages to evade the android and follows him to the Red Ribbon Army's base.

Piccolo disguises himself as a Red Ribbon soldier to infiltrate a Red Ribbon meeting, learning that Gamma 2 was created by Hedo along with Gamma 1 as superheroes to deal with the Z-Fighters and that Hedo reluctantly used his grandfather's schematics on Cell to create an improved version, known as Cell Max. Piccolo informs Bulma of the situation and asks her to contact Goku and Vegeta, while convincing Dende to upgrade the Dragon Balls so he can use a wish from Shenron to unlock his full potential. After completing the wish while learning that Bulma has been unable to contact Whis, Piccolo learns of Magenta's scheme to kidnap Pan in order to lure Gohan into a trap. Piccolo volunteers himself for the kidnapping party and talks Pan into playing along. Enraged upon learning of his daughter's "abduction", Gohan reawakens his Super Saiyan transformation, launches a full-scale assault on the Red Ribbon base and fights Gamma 1. Gohan powers up to his "Ultimate" form during his fight with Gamma 1 while Piccolo discards his disguise to face Gamma 2, with his full potential manifesting in a new form dubbed "Orange Piccolo". Piccolo manages to convince Gamma 2 that Magenta was lying about the Z-Fighters, and the Gammas have a change of heart. Carmine is knocked out by Pan after attempting to kill her, while a furious Magenta runs off to activate Cell Max.

Hedo shoots Magenta dead, but is unable to stop Cell Max's activation. Cell Max emerges as a giant, rampaging monster, while Bulma arrives with Goten, Trunks, Android 18 and Krillin as reinforcements. Gohan, Piccolo, the Gammas and the other fighters battle Cell Max. Goten and Trunks try to fuse into Gotenks, but their fusion technique is imperfect; however, Gotenks does manage to crack Cell Max's skull, revealing that he does not have a regeneration ability like the original Cell. Gamma 2 sacrifices himself in an attempt to kill Cell Max, but only succeeds in destroying Cell Max's left arm. Piccolo battles Cell Max by combining his "Orange Piccolo" and "Great Namekian" forms, but is overwhelmed and brutally beaten. This causes Gohan's inner rage to erupt, and he unlocks an evolution of his "Ultimate" form called "Beast Gohan". Piccolo restrains Cell Max while Gohan fires a supercharged Special Beam Cannon, which pierces through the nucleus in Cell Max's head and kills him. With the battle over, Gohan is reunited with Pan, while a repentant Hedo and Gamma 1 are given positions at Capsule Corporation.