Police Academy 6: City Under Siege is a 1989 American comedy crime film starring Bubba Smith, David Graf and Michael Winslow. It was directed by Peter Bonerz and written by Stephen Curwick, based on characters created by Neal Israel and Pat Proft. The sixth installment in the Police Academy franchise, it is the sequel to Police Academy 5: Assignment Miami Beach. The film was given a PG rating for violence and language. This was the fifth and last Police Academy sequel to be released in the year immediately following the previous installment of the series. It would take five years until the release of the following film, Police Academy: Mission to Moscow. Police Academy 6: City Under Siege was also the last film in the series to feature Bubba Smith, Marion Ramsey, Bruce Mahler, Lance Kinsey and George R. Robertson as Moses Hightower, Laverne Hooks, Douglas Fackler, Carl Proctor and Commissioner Henry Hurst respectively.

In the city, the police are investigating a series of robberies along the old 51 bus route in the area of the city known as Wilson Heights. Captain Thaddeus Harris and Lt. Carl Proctor stake out a jewellery store, but the Wilson Heights gang, composed of Ace, a skilled gunman, Flash, an acrobatic martial artist, and Ox, a strong man, manage to elude capture.

In his office, the mayor is furious with the latest crime spree and reprimands Harris and Commissioner Henry Hurst for his precinct's slow response. The governor is involved now, therefore, has brought in a special team led by Commandant Eric Lassard to stop the robberies. The mayor orders Harris and Hurst to work with Lassard to apprehend the gang. Lassard assembles a seven-man team consisting of gentle-giant Moses Hightower, weapon-crazy Eugene Tackleberry, human beatbox Larvell Jones, passive-aggressive Laverne Hooks, tough and hot Debbie Callahan, accident-prone Douglas Fackler, and Lassard's nephew, Nick from Miami.

At the site of the gang's latest robbery, a bank, the police academy team discovers clues that suggest that the Wilson Heights gang are being orchestrated by some other shadowy figure. After canvassing the neighborhood for any information on the Wilson Heights gang with little success, Nick stumbles upon a paper reporting a priceless diamond heading to a museum, and gets an idea to use it as bait. However, the robbers nab the diamond anyway by cutting a hole in the truck using a laser and escaping through the sewer system. Nick then decides to go undercover to get information regarding a possible hideout, but Harris insists on going instead, and botches the job after Proctor accidentally knocks him over the balcony. Lassard and his men are later suspended after jewelry from the gang's last robbery is found in Lassard's office, pending an investigation.

The team decides to clear his name by investigating and solving the crimes themselves. Having Hooks access data files from a computer, Nick deduces that the robberies are occurring along the old bus line in the city, thus intentionally lowering property values in that part of the city prior to the announcement of a new replacement line system. They also learn that someone must be leaking information to the criminals, which is why they are always one step ahead of the police.

The police academy force finds and does battle with the Wilson Heights criminals during a citywide blackout, Tackleberry taking down Ace, Jones defeating Flash, and Hightower beating Ox, while Nick chases the leader. A pursuit follows, which leads to Hurst's office, where they find Hurst. But, after the real Hurst arrives, Hightower unmasks the fake Hurst to reveal that the mastermind has been the mayor all along. Caught, the mayor admits that Harris has been unwittingly leaking information during his daily meetings with him, and how he could have made billions off the properties if it hadn't been for Lassard and his team. Hurst then apologizes to Lassard and reinstates him and his team, and a plaque is given to honor the officers' bravery the next day.

The movie ends with Harris being flown away by a bunch of balloons attached to his chair during the ceremony; thanks to Lassard.

Police Academy 6: City Under Siege was filmed in Los Angeles, California.