The Timekeeper is a villain who possesses a powerful device called the "Timekeeper" which has the ability to stop time. He plans to use it to take over the world and plunge it into a timeless state, where he would rule as the ultimate dictator. To stop him, Marissa and her stepchildren must travel through time to collect and assemble the medallions that power the Timekeeper.
Along the way, they encounter various challenges and obstacles, including a group of robot henchmen and a rival spy organization led by an old acquaintance of Marissa's. Rebecca and Cecil initially resent their stepmother but gradually come to appreciate her skills and courage, while also learning important lessons about family and teamwork.
Meanwhile, Carmen and Juni, now adults and successful inventors, assist the group with high-tech gadgets and vehicles. They also provide comic relief and occasional references to the earlier films in the franchise.
The film features a mix of live-action and animated sequences, as well as a new cast of child actors as the protagonists. It was directed by Robert Rodriguez, who also created and co-wrote the screenplay. Other notable cast members include Joel McHale as Marissa's husband and comedian Ricky Gervais as the voice of the family dog, Argonaut.