As the charming wildlife community of Liberty Park basks in the afterglow of Norvirus Raccoon's defeat, Surly Squirrel enjoys a newfound celebrity status among his fellow critters. The once humble Maury's Nut Shop, now known as Nibbler’s Nut Shop, serves as a beloved buffet spot, but Andie, with her more pragmatic mindset, begins to disrupt Surly’s laid-back way of living. Despite Mole’s well-intended but clumsy attempts at running the nut shop, a catastrophic accident leaves the establishment in ruins.
Recognizing the need for a shift, Andie suggests returning to their roots by foraging around Liberty Park instead of depending on the nut shop's abundance. Surly, along with Buddy, struggles to find alternative food sources, which deepens their reliance on Nibbler’s. However, they eventually concede to Andie's wisdom as the animals start adapting to this new, more independent lifestyle. Unfortunately, concerns about the park’s financial future lead the corrupt Mayor Percival J. Muldoon to devise a nefarious plan to transform Liberty Park into a gaudy amusement park named Libertyland.
Swiftly uncovering Muldoon's plot, Surly takes charge, urging the animals to thwart the construction workers who threaten their home. Yet their brief triumph is short-lived when Andie's cautions about neglecting practical survival fall on deaf ears. As the mayor's foreman reports alarming animal skirmishes, Gunther leads a relentless extermination team to eliminate the creatures of Liberty Park.
Caught in one of Gunther's snares, Surly, along with Buddy, embarks on a daring mission to rescue Precious, who is in peril. Meanwhile, the remaining park inhabitants must flee their cherished home in search of refuge. Their journey leads them to a formidable colony of white mice under the leadership of Mr. Feng, a challenge they must navigate successfully. After overcoming this hurdle, Surly and Buddy infiltrate Muldoon’s mansion, where they find Precious trapped in the bedroom belonging to the mayor’s spoiled daughter, Heather. Her dismissal of Frankie's affections leaves the canine feeling rejected.
In a reckless twist, Surly's actions inadvertently put Buddy at risk once more, resulting in Buddy falling from a balcony and losing consciousness. As Andie, Jimmy, Johnny, and Jamie discover what they believe to be a perfect new abode, they soon find themselves in peril on a treacherous golf course. Despite their injuries, Andie employs her medical skills to save Jamie using CPR and makeshift methods.
As the remnants of Nibbler's Nut Shop lie in ruins, Surly, Precious, and Buddy reunite with their compatriots. In a heartfelt moment, Surly reflects on their past as outcasts, bound together by shared challenges. This moment of introspection is abruptly cut short when Buddy awakens, thanks to Precious's caring touch.
With the grand opening of Libertyland looming, Surly gathers the animals for a bold offensive to reclaim their park from Muldoon's clutches. As chaos erupts, Muldoon frantically calls for Gunther and his squad, but unperturbed, Surly seeks out Mr. Feng, culminating in a fierce showdown. Surly uses this confrontation to stress the imperative of unity and cooperation among all creatures of the city and park.
Fortified by newfound allies, Surly and the mice launch a daring assault on Libertyland, overwhelming the construction crew and wreaking havoc on the amusement rides. The authorities are soon called in, bringing their antics into the public eye. Amidst the frenzy, Precious finds Frankie and reconciles their relationship, mending past wounds.
As the ruckus subsides, Heather attempts to persuade Gunther to tranquilize the animals, but Surly disrupts her scheme. In an unexpected twist, Gunther accidentally injures Heather while fleeing the chaos. Meanwhile, Muldoon makes a hasty escape via hot air balloon, only to be pursued by Surly and Buddy, who commandeer a roller coaster in a heart-pounding chase.
With the clash intensifying, Muldoon ends up crashing into a bouncy house, where he faces off with Mr. Feng and his martial arts-trained mice. Authorities soon arrive, apprehending Muldoon, Heather, and Gunther for their roles in the bedlam. Libertyland faces permanent closure as a result.
Months later, the community unites to restore Liberty Park to its former vibrancy. The park rejuvenates as Mr. Feng and his colony master their Tai Chi moves, while Precious and Frankie celebrate the arrival of new pups into their lives. Meanwhile, Surly takes Andie on a thrilling escapade, targeting a nut cart in the process.
In a whimsical post-credits scene, the ever-cunning Raccoon is seen plotting his revenge, oblivious to the lurking danger of a school of sharks lying in wait to strike.
