Friday and Gannon encounter Benjy "Blue Boy" Carver, an LSD user. Because of the then-lack of any laws against the use of LSD, they are unable to make a case against him, and Carver's parents are of no help. Finally, legislation is passed against LSD use and sale, but by then it may be too late for "Blue Boy".
Friday and Gannon are working the day watch out of burglary division when they hear that a large quantity of high velocity gelatin dynamite has been stolen from a construction site. When they interview the Night Watchman who tried to stop the crime they get a license plate # for the car involved. Further investigating leads them to a bar patron nicknamed Ziggy. When they finally track him down they find that four of the eight stolen cases are empty and set to go off somewhere in the city.
Friday and Gannon are working the day watch out of homicide when a phone call comes in from Ray Righetti, the manager of the Universal City branch of the Bank of America. Janet Ohrmund claims to have information of a kidnapping and ransom demand. When they question her she tells them a young man is holding her employer Adele Vincent hostage for $75,000. She was told to get the money or else he will kill her.
Friday and Gannon question Officer Paul Culver, on the job only 114 days and currently working undercover out of the narcotics division, about the armed robbery of a liquor store in Hollywood. Despite a positive identification in the line-up and thinking he failed the lie-detector tests, Culver swears he is innocent.
Friday and Gannon try to stop a string of robberies by men wearing red masks. A red Cadillac and tip from a drive-in theater waitress lead the pair to a juvenile who may be the key to discovering the identity of the gang members.
Friday and Gannon are working the day watch out of Frauds Division, Bunco Section. An expert pair of confidence men have moved from Seattle into L.A. Their victims are the elderly and they have been very successful. They pose as bank examiners out to catch crooked tellers and cheat their victims out of their savings. Friday and Gannon will have to catch them in the process of an actual swindle if they are to make a case against them stick.
The manager of an apartment building is beaten to death with a hammer. Clues at the scene point to a man named 'Fred', who was playing cards with the victim. Fred has fled, possibly in another tenant's car. Later, Friday gets a call notifying him that Frederick Tosca and his girlfriend are in custody in Arizona. Extradition papers are prepared and Friday, Gannon, and Policewoman Dorothy Miller head to Cottonwood. Tosca admits nothing, but a search of the stolen car turns up a key piece of evidence.
In the span of two weeks someone has robbed at gunpoint ten branches of the city's largest candy store chain--Rachelles. The suspect is described as an older man thin and gaunt. He's never held up the same store twice so Friday organizes two man teams to stakeout the remaining five stores. Just when they think they've figured out his MO he hits the same store twice.
Emile Hartman reports the theft of $100,000 worth of quality furs and his delivery van. Friday and Gannon aren't having much luck until an insurance agent reports a call from a man selling fur coats. When he calls back a meeting is set up. The furrier must then give Gannon a crash course in furs so the detectives can pose as buyers to make the arrest.
A woman claims someone broke into her home and stole her valuable jade jewelery. When Friday and Gannon investigate, they cannot get a straight story from the woman, and they start to think it might be insurance fraud.
A police officer is shot during a routine stop of a car. Friday and Gannon find the driver and passenger, and learn they are paroled convicts. The police officer cannot remember anything about the shooting event to help convict the two men.
Friday becomes emotionally involved in a rape-murder case of a Japanese-American war widow, especially after he sees how beautiful she was and after he finds out that she left a young daughter behind. Also, there might be a connection with the rape of another woman the previous night. Now Friday and Gannon must search for the rapist before he strikes again.
A teenage shoplifting gang is targeting a group of stores. It turns out the kids belong to a club, The Mod Squad, which requires them to steal $20 in clothes. Friday and Gannon go to the high school to talk to the boys before they get into more trouble.
Friday and Gannon are working the day watch out of homicide when they respond to a late night call at the house of Jessie Gaynor. Her daughter Nora Hamlin is staying with her due to a separation from her husband. The call involves a gunshot heard from a locked study where Carl Hamlin's body is discovered. It is assumed at first that he killed himself but when Ray Murray from SID tells them that the bullet doesn't match the gun it turns into a murder case.