As Lou Pickles' wedding reception to Lulu draws to a close, a wave of melancholy envelops Chuckie Finster, causing him to reflect on his late mother, whose absence has left a gaping void in his life. This poignant moment stirs something within Chas Finster, prompting him to consider the possibility of remarrying, as both father and son grapple with this palpable loss.
Simultaneously, Tommy Pickles' father, Stu Pickles, receives an urgent call from EuroReptarland, a Japanese-themed amusement park in Paris, where he is tasked with fixing a malfunctioning Reptar robot meant to star in the park’s stage show. This summons compels the entire Pickles, Finster, and DeVille families to embark on a journey to EuroReptarland, overseen by the mysterious Coco LaBouche.
Coco's ambitions become clear as she manipulates the situation to outmaneuver her superior, Mr. Yamaguchi, to become the president of the Reptar corporation. Her scheme involves misleading Yamaguchi into believing she is engaged to a man with a child. However, this deception is uncovered by Angelica Pickles, leading her to expose Chas’s interest in remarrying as a way to divert attention from her own predicament.
With the stage set for significant changes within the family dynamics, Chuckie becomes determined to uncover the truth behind the animatronic princess, yearning for the maternal love he longs for. Teaming up with his friends and Kimi Watanabe, daughter of Kira Watanabe, he embarks on a quest through EuroReptarland to unravel the mysteries of Reptar’s past and the princess connected to his heart.
Meanwhile, Spike, the loyal dog of the Pickles, loses his way while pursuing Fifi, a charming stray poodle. As the families explore the amusement park's wonders and face the ensuing challenges, Coco's devious plans continue to unfold, building towards a tense climax that will shape the Finster family’s future.
Amidst the confusion, Chuckie remains wary of Coco’s true motives, even as Chas begins to recognize the potential benefits of starting anew through marriage. Tension peaks on the wedding day when Angelica, who has been diligently exposing Coco's schemes, reveals her true colors just as Chuckie makes a decisive stand by proclaiming "No!" to halt the wedding. This unanticipated interruption leads to the revelation of Coco's dishonest actions, prompting Chas to reject the ceremony in disgust.
The fallout from Coco's treachery is immediate, culminating in her dismissal by Mr. Yamaguchi and mockery from Angelica, amplifying her humiliation. In the chaos, Chuckie and Chas confront the consequences, leading to heartfelt apologies from Kira and awakening mutual feelings between her and Chas. In a touching finale, the Finsters and Watanabes come together to form a new blended family, with Fifi finding love and a nurturing environment among her new parents.
