As Commandant Eric Lassard devises a solution to combat the escalating challenges of overwork and understaffing, he introduces an innovative yet unconventional initiative dubbed "Citizens On Patrol" (COP). This program strategically pairs enthusiastic civilian volunteers with experienced officers in a joint effort to address community issues. Among the spirited group led by Carey Mahoney are a diverse bunch of misfits, including Moses Hightower, Larvell Jones, Eugene Tackleberry, Zed, Sweetchuck, Laverne Hooks, and Debbie Callahan, all set to mentor the eager recruits.
The recruits themselves are an eclectic mix of characters, including the imposing Tommy "House" Conklin, a gentle giant with a history of being babysat by Hightower, an exuberant senior citizen named Lois Feldman, and Tackleberry's unconventional father-in-law. There are also two skateboarders, Kyle and Arnie, who attract the critical eye of none other than Captain Harris. Mahoney manages to convince Judge Butterworth to offer these troublemakers a break from a lengthy sentence by allowing them to participate in the COP program instead.
However, resistance brews as Captain Harris is less than pleased with Lassard's unconventional approach and aims to undermine the entire program. With the Commandant away at an international conference, Harris seizes the opportunity to commandeer the academy and hatch plans to dismantle the COP initiative. Enlisted for support is his loyal aide, Lt. Proctor, who assists in their schemes to discredit the well-meaning volunteers and restore traditional order to the police force.
Despite the odds stacked against them, the spirited volunteers flourish in their training sessions under Mahoney's mentorship. Mrs. Feldman surprises everyone by demonstrating her proficiency with Tackleberry's powerful .44 Magnum, while she forms an unexpected connection with her instructor. Additionally, Zed finds himself captivated by Laura, a journalist-photographer who reports on Lassard's pioneering COP program. Her admiration grows as she witnesses Zed's bravery during crucial water safety drills. Yet, Harris's dismissive remarks only ignite Zed's desire for retribution, which manifests in a well-timed can of mace that leaves Captain Harris with a pungent reminder of his arrogance.
As playful pranks and tensions escalate, Jones learns that some recruits—House, Kyle, and Arnie—are eager to step up their training. In a moment of levity, Mahoney, Hightower, Tackleberry, and Jones decide to prank them by trapping them in a prisoner transport van alongside an "undead" Tackleberry, courtesy of Hightower's questionable voodoo skills, and an overzealous maniac wielding a chainsaw. Following a stern reprimand from Captain Harris, Zed finds solace with Laura, who commends his dedication to the COP program.
However, after a disastrous undercover operation leads to the temporary suspension of the Community Oriented Policing program, Harris initially revels in his perceived victory. Yet, Mahoney's clever act of revenge—gluing Harris's bullhorn to his mouth—significantly shifts the balance. In the midst of a high-profile tour for esteemed citizens, Proctor inadvertently causes chaos by releasing all inmates from precinct 19, leading to a frenzied scene involving escaped criminals, ninjas, and a special appearance by Randall "Tex" Cobb.
As pandemonium unfolds with Harris and his guests taken hostage, they boisterously escape into the streets, only to run directly into Mrs. Feldman, who promptly informs the Lassard academy of the situation. In response, COP volunteers, alongside regular officers, spring into action to recapture the escapees, thwarting their plans for further chaos, including foiled robberies and a hair-raising high-speed chase in a hot air balloon. Meanwhile, House, Kyle, Arnie, and Judge Butterworth come to the rescue of both Harris and Proctor, who are struggling to stay afloat after their ill-fated attempt to join the impetus.
As the turbulent events subside, Zed's heroic act of saving Sweetchuck during a dramatic fall from a plane earns him the admiration of Laura. The police chiefs who observe Lassard's program at work cannot help but praise its effectiveness, much to Captain Harris's chagrin.
