The protagonist unexpectedly transmigrates into the world of The Little Piece Family: Rookie Agent, becoming Jack of Clubs, a senior researcher in the Playing Card Organization. The original owner was loyal to the dictatorial villain King of Spades, helping with live-subject experiments on Clone Island and the development of a clone army. With modern values, the protagonist resolves to go undercover and turn against him.
In the original mecha battle storyline, the protagonist pretends to control the Mechanical Black Tortoise against Xiao Pin, secretly holding back. After losing, he uses the opportunity to contact Xiao Pin in private, pass along crucial intelligence, and urge him to release eight convicted criminals with SS-rank superpowers. Back on Clone Island, he uses his research authority to win over every number-card member, including Two of Diamonds and Three of Clubs. He also presents evidence that persuades the deputy leader, Nine of Spades, to defect in secret. Their side quietly takes shape.
The decisive battle begins. Xiao Pin keeps the King of Spades occupied head-on while the allied forces launch an all-out assault. But the King of Spades unleashes a vast army of mass-produced clones, driving them into a desperate corner. At the critical moment, the eight superpowered criminals break out of their cages and appear, joining forces to crush the clone army. The King of Spades reveals his trump card: he can transfer his consciousness into clone bodies indefinitely, making him impossible to kill, and he also has a hidden clone production line.
The protagonist leads a daring assault on the high platform. After a fierce battle, they destroy the source crystal sustaining clone production, cutting off the King of Spades’ ability to switch bodies and make soldiers. With nowhere left to turn, the King of Spades reveals his long-hidden trump card: a modified clone army. In the end, everyone joins forces to capture him.
After the battle, they reveal that everyone is a transmigrator from another world, except the King of Spades, who is a native villain. The villain is thrown into prison, and the battle finally ends. The protagonist returns to reality without a hitch, only to suddenly remember that he still has a mountain of homework to finish.
