The misfit Police Academy (1984) graduates now are assigned to train a group of civilian volunteers to fight crime once again plaguing the streets.
A new batch of recruits arrives at Police Academy, this time a group of civilian volunteers who have joined Commandant Lassard's new Citizens on Patrol program. Although the community relations project has strong governmental support, a disgusted Captain Harris is determined to see it fail.
Commandant Eric Lassard decides that the police force is overworked and understaffed, so he comes up with the idea of recruiting civilian volunteers to work side-by-side with officers in a program called "Citizens On Patrol" (COP). Carey Mahoney and his friends Moses Hightower, Larvell Jones, Eugene Tackleberry, Laverne Hooks, and Debbie Callahan are in charge of training the civilians. The civilians include Tommy "House" Conklin, Lois Feldman, Kyle, and Arnie. Captain Thaddeus Harris wants to take over Lassard's job, and that's why Harris is determined to see the COP program fail. But it's Harris and his right hand man Proctor who mess up by unintentionally allowing every inmate at the precinct 19 jail to escape.
- Police Academy head Commandant Eric Lassard (George Gaynes) decides that the police force is overworked and understaffed, so he comes up with the idea of recruiting civilian volunteers to work side-by-side with his officers in a program called "Citizens On Patrol" (COP). Fellow alumni Carey Mahoney (Steve Guttenberg) and his friends Moses Hightower (Bubba Smith), Larvell Jones (Michael Winslow), Eugene Tackleberry (David Graf), Zed (Bobcat Goldthwait), Sweetchuck (Tim Kazurinsky), Laverne Hooks (Marion Ramsey), and Debbie Callahan (Leslie Easterbrook) are in charge of training the civilians. The civilians include the enormous obese Tommy "House" Conklin (Tab Thacker), gung-ho senior citizen Lois Feldman (Billie Bird), and two skateboarding delinquents Kyle (David Spade) and Arnie (Brian Backer).
However, the veteran academy trainer, Captain Thaddeus Harris (G.W. Bailey) believes "the concept of citizens doing police work is asinine" and plans to take over Lassard's job, and that's why Harris is determined to see the COP program fail, and to work on a plan to discredit Mahoney (whom Harris has had a grudge against ever since the very first movie). When Lassard leaves on an overseas conference, Harris, along with his dull-witted right hand man Lt. Proctor (Lance Kinsey), are put in charge of the academy and Harris immedietely plots to make the COP volunteers quit and leave the police work to the officers.
The volunteers do well in their training, Mrs. Feldman excelling in firing Tackleberry's .44 Magnum. In training for water safety and drowning victim rescue, Zed "rescues" a cadet but experiences a personal loss of his no longer functioning watch, and mourns the death of the cartoon character inside of it saying it was the last thing he ever stole before joining the academy. Through his loss Zed gains a love interest, Laura (Corinne Bohrer), a reporter/photographer who has come to the academy to view Lassard's COP program and takes a fancy to former gang leader Zed. Unfortunately Harris ruins the moment and insults Zed and Laura, which causes Zed to replace Harris's deoderant with mace. In the next scene while Zed instructs the volunteers on the very important matter of how to correctly eat a donut, Harris is seen wearing a medical device suspending his arms in the air. Despite the pranks played upon him during the various training exercises the volunteers take, Harris is determined to make the Citizens on Patrol program fail.
Meanwhile, Jones learns that volunteers House, Kyle, and Arnie believe themselves ready to go out and catch criminals, so Jones, Mahoney, Hightower, and Tackleberry play a prank on the boys to make them take their training more seriously. Mahoney and Jones fake an arrest with Hightower playing a voodoo priest, and Tackleberry playing a hockey-masked chainsaw wielding maniac to successfully scare the boys.
The next day, after being yelled at again by Captain Harris and being called a disgrace, Zed is comforted again by Laura, who says she thinks he's perfect.
After several volunteers foil an undercover police sting, the Citizens on Patrol program is suspended, much to Harris's delight. While Harris gives a tour of his precinct to a group of foreign dignitaries, the numb-skull Proctor messes up and is tricked by the inmates into releasing every inmate at the Precinct 19 jail, including a team of ninjas, and a redneck thug gang leader (Randall "Tex" Cobb), who had taken Zed's place as leader of the gang back after Zed's arrest in Police Academy 2.
When Lassard's officers hear of the jailbreak, the COP volunteers are dispatched along with the regular officers to catch the escaped felons, which include a team of ninja warriors. After Jones, Hightower and Lois Feldman stop a robbery, Mahoney and Tackleberry take a high speed air balloon to chase after another group of robbers. As a result, the felons are all recaptured. Meanwhile, House, Kyle, and Arnie save Harris and Proctor from drowning in a river. And Zed impresses Laura by saving Sweetchuck's life after they both fall out of a plane in mid-air.
The several police chiefs who came to witness Lassard's program in action congratulate and compliment Lassard on his program and his officers.