Plot

Carmen's caught in a virtual reality game designed by the Kids' new nemesis, the Toymaker. It's up to Juni to save his sister, and ultimately the world.

Under-age agents Juni and Carmen Cortez set out on their newest most mind-blowing mission yet: journeying inside the virtual reality world of a 3-D video game designed to outsmart them, as the awe-inspiring graphics and creatures of gaming come to real life. Relying on humor, gadgetry, bravery, family bonds and lightning-quick reflexes, the Spy Kids must battle through tougher and tougher levels of the game, facing challenges that include racing against road warriors and surfing on boiling lava, in order to save the world from a power hungry villain.—Anthony Pereyra <hypersonic91@yahoo.com>

With the help of allies, two siblings and their grandfather enter a video game to defeat a great enemy and stop him escaping and take over the world. Along the way, they discover who they really are and call in support from every possible direction.—RECB3

Juni Cortez has now retired from being a spy and is trying to live a normal life. But he gets thrown back into the spy world, when his sister Carmen Cortez is kidnapped by the Toymaker. Carmen is trapped inside the Toymaker's video game, and the only way Juni can reach her is by going into the third dimensional world himself.—FilmFanUK

Juni Cortez, (Daryl Sabara) no longer an agent of the OSS, now works as a private detective but gets little profit for his work ($4.99). He is contacted by the OSS and informed that his sister, Carmen Cortez, (Alexa Vega) is missing. He is reunited with Donnagon Giggles and his wife Francesca, who explain that Carmen was captured by the Toymaker (Sylvester Stallone), a villain. The Toymaker was imprisoned in cyberspace by the OSS, but he has since created "Game Over" a virtual reality-based video game which he intends on using to escape cyberspace via players that reach Level 5, which is literally unwinnable. Juni agrees to venture into the game, save Carmen, and shut down the game.

In the game, which takes place in a full 3D environment, Juni finds the challenges difficult. He finds three beta-testers, Francis (Bobby Edner), Arnold (Ryan Pinkston) and Rez (Robert Vito), who launch him to the moon so that they'll have less competition on the way to Level 5. On the moon, Juni receives an opportunity to bring in a fellow ally to assist him, selecting his grandfather, who has been looking for the Toymaker for years.

He receives a power-up which gives him a robotic suit allowing him to walk. Juni ventures into a robot battle arena where he fights a girl named Demetra (Courtney Jines) in order to return to Earth and Level 2. He meets the beta-testers again who believe he is a player named "The Guy", who can supposedly beat Level 5. Rez is unconvinced and challenges Juni to a "Mega-race" involving a multitude of different vehicles. The only apparent rule of this game is "Win, at all costs."

Juni wins the race with help from Valentin, and Demetra joins the group, she and Juni display romantic feelings for each other. Upon entering level 3, Arnold and Juni are forced to battle each other, the loser getting an immediate game over. Demetra swaps places with Juni and is defeated, seemingly getting a game over, much to Juni's sadness.

The group get to Level 4 where Juni finds Carmen, released by the Toymaker, who leads the group on. Juni follows a map given to him by Demetra to a lava-filled gorge. The group surf their way through the lava, but Donnagan attempts to prevent them from reaching Level 5 to save them, but this fails. Outside the door to Level 5, after the other gamer start to think that Carmen and Juni are the deceivers and Rez threatening to give Juni a game over, the real "Guy" (Elijah Wood) appears and opens the door only to get a game over by an electrical shock (losing all of his apparent, 100 lives).

Demetra appears, claiming to have got back into the game via a glitch but Carmen identifies her as The Deceiver, a program used to fool players. Demetra confirms this and apologizes to Juni. The Toymaker attacks the group with giant robot, Demetra shedding a tear and shutting the game down so Juni and the others can return to reality. However, it is revealed that Valentin released the Toymaker, the villain's army of robots attacking a nearby city.

Juni and Carmen summon their family members: Parents Gregorio and Ingrid, Gregorio's brother Machete, their Grandma, and Uncle Felix. With too many robots to handle, Juni calls out to their "extended" family, summoning characters from the first two films (including Fegan Floop and Alexander Minion, Dinky Winks and his son, scientist Romero (plus a Spork), and Gary and Gerti Giggles). The robots are destroyed except the Toymaker's. Valentin confronts Sebastian the Toymaker and reveals that it was he who put him in the wheelchair, but forgives Sebastian the Toymaker for his actions, which is why he was perching on his shoulders all those years.

Sebastian the Toymaker shuts down his robot and joins the rest of the Cortez family and their friends to celebrate their family leaving the possibility of another sequel.