Captain Harris finally found a way to become Commandant of the Police Academy; the current incumbent, Commandant Lassard, is past due for mandatory retirement. Meanwhile, Lassard is chosen as "Police Officer of the Decade," and brings his favorite graduates—Sgts. Hightower, Jones, Tackleberry and Hooks, Lt. Callahan, and new graduate Officer Thomas "House" Conklin—to the National Police Chiefs Convention in Miami Beach to celebrate with him. The city council postpones the retirement until after Lassard's return. While there, they meet his nephew, Sgt. Nick Lassard of the Miami Police Department. Lassard unwittingly takes a bag belonging to jewel thieves containing stolen diamonds.
As the jewel thieves try to get the bag back, and Captain Harris tries to prove to Commissioner Hurst that he is the right man to replace Commandant Lassard, the usual hi-jinks ensue, including Lassard trying to guess the annual procedural demonstration. When the jewel thieves kidnap Commandant Lassard, he goes willingly, thinking it part of the convention. It launches a negotiation, which Captain Harris botches, getting himself captured as well. A chase across the Everglades ensues to rescue the oblivious Commandant. In a standoff with the smugglers, Nick explains to his uncle that the situation is not a demonstration and that his kidnappers are in fact real criminals. Lassard, upon hearing this information, promptly disarms and subdues his assailants to the amazement of all the officers. At a ceremony at the end of the film, Commissioner Hurst announces that Commandant Lassard will be allowed to continue his duties as Commandant until he sees fit to retire, as well as Hightower's promotion to Lieutenant due to him saving Harris's life during the rescue.
Lassard is seen proudly graduating the new class. As form of revenge for Harris' earlier sabotage against his uncle, Nick intentionally moves the chair away from Harris. Proctor tries to help him, but kicks the chair too hard and sending both it and Harris on a collision into the drum set. As the police marching band walks off in parade, Harris is seen screaming for Proctor to help him.
Michael Winslow as Sgt. Larvell Jones
David Graf as Sgt. Eugene Tackleberry
Bubba Smith as Sgt./Lt. Moses Hightower
Marion Ramsey as Sgt. Laverne Hooks
Leslie Easterbrook as Lt. Debbie Callahan
Tab Thacker as Officer Thomas 'House' Conklin
George Gaynes as Cmdt. Eric Lassard
G. W. Bailey as Capt. Thaddeus Harris
Lance Kinsey as Lt. Carl Proctor
George R. Robertson as Commissioner Henry Hurst
Matt McCoy as Sgt. Nick Lassard
Janet Jones as Officer Kate Stratton
René Auberjonois as Tony
Archie Hahn as Mouse
James Hampton as Mayor of Miami
Ed Kovens as Dempsey
Scott Weinger as Shark Attack Kid
Julio Oscar Mechoso as Shooting Range Cop
Joe Del Campo as Convention Man
Jerry O'Connell as Beach Kid
Paul Maslansky as Homeless Man
Graham Smith as Custody Sergeant S.Chlong
fifth installment in the Police Academy franchise