At the wedding reception of Lou Pickles and his new wife Lulu, a mother-child dance saddens
Chuckie Finster with memories of his mother, who died shortly after his birth. Realizing that he and his son miss that female influence in their lives, Chuckie's father Chas starts thinking of remarriage.
Tommy Pickles' father Stu is then summoned to EuroReptarland, a Japanese amusement park in Paris, to fix a malfunctioning
Reptar robot he designed for the park's stage show. The Pickles, Finster and DeVille families travel to EuroReptarland, run by the ill-tempered and child-hating Coco LaBouche, who desires to succeed her supervisor, Mr. Yamaguchi, as president of the Reptar corporation.
Angelica Pickles overhears Coco falsely informing Yamaguchi, who insists his successor must love children, that she is engaged to a man with a child. Yamaguchi says he will consider her promotion once he has attended her wedding. Angelica is then discovered eavesdropping and saves herself by telling Coco about Chas. Coco begins pursuing Chas with the help of her put-upon but kindhearted assistant, Kira Watanabe, who tells the babies how Reptar was a feared monster before his gentler side was revealed by a princess. Hearing this, Chuckie decides he wants the princess to be his mother. Meanwhile, the Pickles' dog Spike wanders the Parisian streets and falls in love with a stray poodle named Fifi. While Coco wins over Chas, Chuckie remains deeply distrustful of her. At the Reptar show's premiere, Angelica informs Coco of Chuckie's wish to have the princess for his mother, prompting Coco to infiltrate the show disguised as the princess. She lures Chuckie on stage, where he is horrified to see her true identity; however, seeing his son go to Coco convinces Chas that he should marry her immediately. On her wedding day, Coco orders her accomplice, Jean-Claude, to keep the babies and Angelica from intervening. Kira learns of Coco's plot and threatens to tell Chas but gets thrown out en route to the ceremony and hurries there by bicycle. Meanwhile, Jean-Claude imprisons the children in the warehouse where the show's robots are kept. When Chuckie despairs over the situation, a guilt-ridden Angelica reveals Coco's plan and her part in it. Following the revelation, Chuckie rallies the others to stop the wedding and they hurry to
Notre Dame in the Reptar robot, while picking up Kira's daughter, Kimi, along the way. Jean-Claude pursues them in the animatronic of Reptar's nemesis, Robosnail; the two eventually fight and the babies use Reptar to knock Robosnail into the
Seine River. Chuckie arrives at the cathedral and stops the wedding by saying out his first word, "No!". After Jean-Claude and Angelica reveal Coco's plot and true nature, a disgusted Chas calls off the wedding and Yamaguchi dismisses her. When Coco makes some of the babies fall to the floor as she attempts to leave, Angelica rips her dress by stepping on it. A humiliated Coco flees the cathedral, while Spike chases Jean-Claude away. As Chas apologizes to Chuckie for everything Coco put them both through, Kira arrives and apologizes to him for not speaking up sooner. Realizing they have much in common, Chas and Kira develop feelings for each other. Returning home, they marry and the Finsters and Watanabes, who also adopt Fifi, become a new family. ==Voice cast==