A struggling comedian owes money to the owner of a nightclub. When his body is discovered at the bottom of a cliff in a car crash, all the clues point to suicide. It is later discovered that the comedian was also a police informant on a drug ring he infiltrated at his nightclub. Frank steps in and takes the place of the deceased at the nightclub in order to gather more clues.

The mob sets up an "insurance" scam that threatens several businesses and residents. Frank and Nordberg go to investigate. After a dance instructor is beaten up, they set up their own shop - a key-making and locksmith store - and go undercover. When the mob stops by to offer them "insurance", Frank dismisses their threats and the mob strikes their store. Frank ends up having the key to stopping the crime wave, largely because of the key-making and locksmith shop he and Nordberg set up.

Frank investigates a district judge's courtroom after it is booby-trapped with a powerful explosive. The main suspect is a recently paroled ex-convict with a history of similar bombings. Upon questioning the bomber's ex-wife, Frank and Ed find she's more interested in getting charity than the fact that her ex-husband may be up to his old tricks. Frank and Ed discover the bomber has a showgirl girlfriend on the side. She has the perfect alibi for her boyfriend, but Frank and Ed wonder if she's really just covering for him.

The daughter of a wealthy business man is kidnapped on her 18th birthday and Police Squad swings into action. The main suspect of their investigation is the girl's boyfriend. When Frank and Ed listen to a recording of the kidnapper's demands, they hear the distinct sound of a tuba in the background, though it could also be a ship's horn. They search for a tuba store. When they do track down and find the kidnapper, the criminal fights back.

Frank investigates a veteran boxer who lately has been throwing his fights. He takes the boxer under his wing in order to expose the boxer's corrupt manager. Unfortunately, the manger has kidnapped the boxer's girlfriend and put the boxer's title fight in jeopardy. Frank now tries to save the boxer's girlfriend in the hopes that the boxer won't have to throw the match so he can have a shot at rejuvenating his career in the ring.

Sally, a bank teller deeply in debt, robs her own bank and plants evidence that implicates a fairly commonplace man who was present during the crime. Police Squad, a special unit of the police force, is called to investigate a double shooting that happened during the robbery. However, the stories just don't add up. The evidence builds and points in Sally's direction, but it's up to Frank to find the clues that will put her away.