The Mayor is the Mastermind. He knew that the properties along the old #51 bus route were going to be very valuable, due to the planned intercity Railink route being built along them, so he hired the Wilson Heights Gang to create a crime wave along that route so the properties would get devalued, which would enable him to buy them all at cheap prices. Then, he would have the gang stop their crime wave, and he would retire from office and earn a fortune on the properties through the Railink.
Capt. Harris was his informant, but an unwitting one. His daily reports to the Mayor were what allowed the Mayor and the gang to always stay one step ahead of the officers.
Cmdt. Lassard and his crew manage to uncover the Mayor and his scheme and arrest both him and the gang, and they all receive the Distinguished Service Medal for their success.
After Cmdt. Lassard (George Gaynes) and his team come too close to arresting the Wilson Heights Gang one day, the Mastermind decides to get them out of the way by planting jewelry that the gang had stolen in Lassard’s office, and then sending a tip to the precinct about it. Commissioner Hurst (George R. Robertson) calls Lassard and his team together for a special meeting in the strategy room and presents the stolen items, and tells them about how they were found in Lassard’s office. The also-present Mayor (Kenneth Mars) then announces that Lassard and his team are now suspended pending an investigation.
Undaunted, Lassard’s team resolve to capture the gang and the Mastermind and clear Lassard’s name. They enter the city records room to determine why the robberies are all occurring along the old #51 bus route, and they find out that the planned intercity Railink system is going to be built along that old route. Sgt. Nick Lassard (Matt McCoy) deduces that the crime wave is happening along there so the properties will get devalued, which would enable someone to buy them up cheap, and then they could earn a fortune on them through the Railink system. They are unable to find out who is buying up all of the the properties, but they check out one of the buildings along the route and find blueprints and dynamite stashed there. After looking at the blueprints, Nick informs the others that the Wilson Heights Gang intends to use all of this to shut the city down (and thus cheapen the properties even more). Moments later, the gang blows up the city’s main power grid, causing a total blackout.
As Nick is patrolling the blackened streets, he spots the gang, and after calling for backup, he follows them. His trail leads him to a manhole cover on a nearby dead end road, and he realizes that they went down into the sewers. Lt. Hightower (Bubba Smith), Sgt. Jones (Michael Winslow), and Sgt. Tackleberry (David Graf) then arrive, and all four men go down after the gang.
A short time into the search, Hightower spots a pebble falling from one of the manholes, so he, Jones and Tackleberry head up it to investigate while Nick continues on down the tunnel to see where it leads to. The three find themselves in an abandoned warehouse and discover the gang waiting for them, but they fight and subdue them. Meanwhile, Nick finds the gang’s hideout, but as soon as he steps into it, he gets locked in, and the Mastermind then confronts him from behind his glass wall and tries to kill him by filling the room with poison gas. However, Hightower rescues him in the nick of time.
Hightower smashes open the glass on the wall, and he and Nick follow the hidden passage behind it after the Mastermind. The passage leads them back up to the streets, where the Mastermind unsuccessfully tries to run them over in a cherry picker truck. Nick manages to jump into the basket while Hightower radios all the cops in the area about where the Mastermind is fleeing. Capt. Harris (G.W. Bailey) and Lt. Proctor (Lance Kinsey) hear the call and head to the scene to intercept. As Jones and Tackleberry are chaining up the gang to a fence to leave for officers they’ve called to the scene, the cherry picker truck passes by, and Nick yells to them that the Mastermind is behind the wheel of it. Hightower shows up seconds later in a monster truck, and after Jones and Tackleberry get in, they chase after the Mastermind.
During the chase (in which Harris and Proctor prove to be of no help at all), Nick gets off of the cherry picker truck and onto the monster truck, and the chase comes to a stop at Commissioner Hurst’s office. They go in shortly after power in the city is restored and find Hurst sitting in his chair, and Nick tells him that they chased the Mastermind into this office. Hurst replies that he isn’t here and that they must get out there and find him. Before they leave, Lassard, Lt. Callahan (Leslie Easterbrook), Sgt. Hooks (Marion Ramsey), Sgt. Fackler (Bruce Mahler), and another Hurst show up, and Harris and Proctor arrive moments later. Each Hurst fingers the other as an imposter, so Nick decides to do the “Pinocchio Test”: Pull their noses to see which one of them is wearing a mask. The standing Hurst turns out to be the real Hurst, and Hightower removes the mask from the sitting Hurst, revealing the Mastermind underneath: The Mayor.
The Mayor reveals to all that Harris was his informant, but an unwitting one. His daily reports to the Mayor were what allowed him and the gang to always stay one step ahead of the officers. When Hurst asks the Mayor why he did what he did, Nick explains the Mayor’s whole real estate scheme, and Hurst has the Mayor taken away. He then apologizes to Lassard and reinstates him and his team.
Lassard, his team, and Harris and Proctor are awarded the Distinguished Service Medal for their success, and Lassard and his men play one last trick on Harris that centers around his fear of heights.
Thanks Tornado Dragon!