Barnaby's cousin, Monroe Jones, a Chicago police sergeant, gets a tip from an informant (Tony Ritter) that the man (Walter Cahill) who murdered his partner six years ago is living in Los Angeles. When Sgt.Jones arrives in L.A. to meet up with Ritter, he is murdered at the airport by the same killer. Monroe's son, Jedediah Romano (J.R.) Jones, arrives in L.A. to track down his father's killer and to avenge his father's death. J.R. goes to Barnaby for help in finding Tony Ritter hoping that Ritter can lead him to Monroe's killer. Barnaby and J.R. follow various leads but it is a phone call that is made while Barnaby is out of the office that leads J.R. to a confrontation alone with his father's killer. Unfortunately for J.R., Cahill is well skilled in karate and easily knocks J.R. out. Just as he is about to kill J.R., Barnaby shows up and shoots Cahill, wounding him so that he can not harm J.R.
In order to get the same recognition as his older brother, Danny Reeves robs laundered gambling money from his father, a syndicate man, and is responsible for the death of a pilot. Barnaby and J.R. investigate for the pilot's wife to find out what really happened to her husband since she does not believe it was an accident.
The members of Trident Diving School hire Barnaby to investigate the death of their colleague. Barnaby meets Carl Everett and his assistant Alice Caldwell who claim to be searching for a sunken treasure. J.R. who is certified in scuba makes dives and searches for clues underwater while Barnaby and Betty do the same on land.
During a fishing vacation Barnaby and J.R. are hired by rancher Tim Carter to investigate a conversation overheard by Carter's daughter,Cassie, on her CB radio. Cassie believes that a hired hand, was the victim of foul play on his way out of town. J.R. uses his knowledge of the lingo used on CB radios to help Barnaby figure out that the disappearance is tied to a drug smuggling operation.
During an attempt to escape from prison, Hopper gets away, two people are killed and Watson is caught and facing a murder charge. Hired to clear Watson, Barnaby tries to find Hopper who is looking for money from a robbery that he committed before going to prison. Bounty hunter Kilgore is also hired to find Watson and get rid of him.
Roger, Al and Lester, three former college fraternity brothers want to solve their financial problems by stealing diamonds. During their preparations Lester is shot by a guard. Barnaby is hired by Lester's wife to try and find the missing man. During the investigation, Barnaby and J.R. uncover and foil the plans that Roger and Al have continued with after Lester's death.
Paul Nugent kills his rich cousin Sandra, hurts himself and fakes a jewel burglary. Sandra had a $1000,000 life insurance policy and Barnaby investigates for the insurance company. Suspicion falls on Lassiter since he and his wife were separated. Meanwhile Betty is charmed and starts dating Paul. Barnaby and J.R. must come to the rescue when Betty finds herself in danger
Matthews and Ryan want to get access to an altered last will of billionaire R.C. Bradley. While holding Margaret Jason against her will, she escapes and falls to her death. Her daughter Linda doubts a suicide and asks Barnaby for help. J.R. becomes infatuated with Linda and he and Barnaby try to find out the connection between Mrs. Jason and Mr. Bradley.
Sheriff Bradden kills the lover of his young unfaithful wife Kitty by copying the ‘Colverton Hangman'. To clear the victim's name, his sister hires Barnaby, who is an old acquaintance of Rolly Bradden. Barnaby finds inconsistencies between this murder and the other murders and he and J.R. investigate to uncover the truth.
Since Vietnam Peggy Landry cares for her husband Tom as he suffers from a weakness of memory. Lee Wallace stabs Stevens and makes his friend Tom believe that he is the murderer. Barnaby is hired anonymously by Peggy when Stevens doesn't show up for work and she fears Tom may have something to do with it. J.R. goes undercover as a worker at the warehouse where the anonymous letter came from in an attempt to find out the facts leading to Stevens death.
The singing sisters Pearl and Ruby - prettier than talented - accidentally kill Harry Dunbar and Pearl steals his rare coin collection. Dunbar's widow hire Barnaby to find out if Dunbar did really drown or if he was murdered. While checking out clubs that Dunbar frequented, Barnaby is told that Dunbar left the club with the sisters and when they try to fence the coins it puts Barnaby and J.R. on their trail. After killing Pearl's boyfriend, Harley and framing his co-worker, Lester for the murder, J.R. poses as a friend of Harley and Lester's to trick the sister into confessing their involvement in the frame and murders.
The ""Valentine Murderer"" already has killed three women after sending them letters and candy. When Betty, who has just moved into a new apartment, also receives a Valentine gift everyone assumes she is next on the killer's list. While Barnaby and J.R. search for the killer, Betty is assigned a police body guard whom she dated briefly. Barnaby and J.R. find the killer but Betty turns out to still be in danger.
The singing sisters Ruby and Pearl Connors from the episode ""Duet for Dying"" join a prison escape and seek Lester Gibson's help to travel to Nashville. His bride Mary Beth asks Barnaby to find Lester. When Ruby and Pearl try to cheat club owner De Marco he forces them to distract gambler Kingston. Eventually Barnaby and J.R. must come to the rescue of Lester and the duo.
Barnaby is hired by wealthy Mr Enright to find his daughter Julie who ran away from home. While waiting outside a parking garage for her boyfriend Steve, Julie hits a man coming out of the garage and not knowing her boyfriend had shot the man, Julie thinks she has killed the man. With the help of her friend, Gloria, Julie tries to hide out and find peace at the ""Garden of Elyseum"". Things are not what they seem at the garden and the leaders hold Julie hostage and demand ransom for her. It is up to Barnaby and J.R. to find and rescue Julie.
In his first big undercover assignment J.R. Jones tries to locate his friend Danny Corman, who joined a private army of mercenaries in order to pay the doctor for his ill wife.J.R. joins the same group of mercenaries and with the help of ""Lobo,"" J.R. and Danny foil a plot to assassinate a Near East dictator.
While call girl Felice dines with André LeClair her boss,Harry burglarizes LeClair's home and shoots and kills a security guard. Barnaby and J.R.investigate for the insurance company and it turns out Harry and his partner Lorette Gray, run an answering service that is a front for a call girl service. While the girls are out with the clients, Harry rips them off.
Attempting to locate Gloria, a runaway wife, Barnaby goes to the small town of Las Mesas, which is deserted due to the fair at Colverton. Earl, Ritchie and Tom plan to rob an armored car transport. They hold Gloria, the remaining townspeople and Barnaby as captives. It is up to J.R. to rescue Barnaby and the others when he can't convince the local authorites that something is wrong in Las Mesas.
Barnaby and J.R go to Lake Crystabol to investigate the death of Dr. Welker for the insurance company. Dr. Welker was killed by a dropping flower pot while outside at Diane Magnus' party. Diane thinks that David, the boy friend of her niece Gwen, is the reincarnation of her husband Thomas, murdered 20 years ago.
Barnaby is hired solve the death of Jack Crandall who had an affair with Tracy Wilder. Barnaby finds out that Jack suspected Tracy's considerably older husband Godfrey to be involved in the death of Tracy's wealthy father during a fire twelve years ago. Tracy has a habit of convincing men to feel sorry for her and then they end up dead, she tries to make J.R. her latest victim.
Barnaby and J.R. go to San Leone to help out an old friend of Barnaby's, Carmine Sandell. Carmine asks Barnaby to find out why his son Joe was killed. When Joe's brother Nick is killed a few days later, Tomás Aguilar becomes the prime suspect. His sister Linda, who has just returned to town, was once drugged and raped by the young Sandells and has spent the last 3 years in a sanitarium because of it.
When discovered while robbing a coin collection Dewey Lassiter, a cocaine addict, kills June. Prime suspect is J.R.'s law school class mate Walt, June's boy friend. To protect his guilty son, famous attorney Gordon Lassiter offers to defend Walt, but frames him instead, leaving it up to J.R. to help Walt prove his innocence.
Shortly before leaving for a fishing trip Barnaby gets a telephone call from a desperate Jennifer Rhodes, whose husband was convicted of kidnapping the Sayers's child eleven years ago due to Barnaby's testimony. Barnaby can rescue her from an attempted suicide. Feeling guilty, he tries to locate a witness for the defense but when the girl Hayley is murdered Barnaby is shattered.
Feeling guilty, Barnaby tries to locate a witness for the defense but when the girl Hayley is murdered Barnaby is shattered. He finds out that Gates, a former police detective, covered up for the kidnappers. During a shooting Gates is seriously injured by Barnaby, but his current boss Kingman doesn't show much efforts to help him.
Amy Vickers is harassed by rejected admirer Mitchell Grady II. She comes to Barnaby looking for help and since Barnaby is busy with another case, J.R. takes the case. Amy needs to take some medical records to her father who is in an out of town hospital so J.R. drives her there. The two of them are followed by Mitch and two of his lackies and they are forced to seek refuge in a cabin. While at the cabin they are terrorized by Mitch and his friends.
Barnaby and Betty go to San Diego to help Glen Wilcox who suspects that several yachts that disappeared in the ""Coronado Triangle"" were hijacked. Dawn, the only survivor of a recent disaster, claims to have seen a giant whirlpool. She covers for Lloyd, one of the highjackers. J.R. goes undercover as a rich playboy to try and be the next victim of the hijackers.
Mrs. Russell hires Barnaby to locate Jenny Hastings, who witnessed a murder that Mrs.Russell's husband is about to go on trial for. Barnaby thinks he has located Jenny in a motel a few miles outside of Colverton and while Barnaby is on the phone having Betty check out the license number, Jenny is abducted by men who are working for Curt Phillips. Phillips wants to make sure that Jenny is not around to testify at the trial. While following them into a forest area Barnaby is wounded by a bullet and left blinded. Escaped Jenny discovers him and both try to flee on foot, pursued by the men. Back at the office J.R. has become concerned since he can't reach Barnaby and he sets out to look for him. J.R. arrives in just the nick of time to rescue Barnaby.
During her vacation Betty visits her friend Phyllis. When a young woman whom she denied help is raped, Betty feels guilty and starts to investigate on her own. Once Barnaby and J.R. realize the danger Betty is putting herself in, J.R. goes out to help Betty. Together they question the previous victims and Betty then decides to pose as bait for the rapist to catch him.
During a restaurant date with Drew Barber, the daughter of Barnaby's client, J.R.'s coffee is drugged, and he passes out on the drive home. He awakes in a strange room and is arrested with accusation of rape. Released on bail, he searches for the man who drugged him, but his attempts to speak with his accuser gets his bail revoked, and he finds himself on the run. Barnaby investigates Barber's past and links him to a murder in Cleveland and the reason for the frame of J.R.
Barnaby is hired by Dorothy Warner to find out whether her missing husband Colby really was a deserter in Vietnam. Trying to locate Warner's war comrade Lee Henderson, Barnaby gets involved in a shooting and a ricochet shot from his gun kills a seemingly innocent bystander. Barnaby and J.R. continue to try and under cover exactly what happened to Colby Warner.
When an eager D.A. threatens with a charge of negligent homicide a shattered Barnaby wants to give up the case, but Dorothy asks him to continue. Barnaby uncovers that several soldiers robbed gold in Vietnam and then deserted. Barnaby and J.R. try to figure out how Colby Warner fits into that picture or if he does at all.
When staying with her ex-roommate, disco dancer Penny, Felicia Norris is shot. Penny believes the attempt was meant for her, and fearing for her life she asks Barnaby for help. Barnaby turns the case over to J.R. While investigating, J.R. finds out that in fact Felicia's husband hired Penny's dancing partner Gary to get rid of his wife.
Shortly after lawyer Adams of Nettleson Corporation withdraws a commission from Barnaby, he is killed. In trying to solve the case, Barnaby and J.R. are assisted by Stephanie Capello, a young colleague of Adams, who tells he was searching for Diana Scott. Diana went to the ""Center for Spiritual Enlightment"".
During the course of their investigations Barnaby gets his license revoked due to a false accusation, and J.R. joins the ""Center"" to find Diana, who turns out to be the illegitimate child of Mimi Nettleson Chiles of Nettleson Corp. and the leader of the religious cult, Garrison, rejected by Mimi's family.
When designer and co-owner Chris Alden is killed in a fire at a company producing swimwear Barnaby investigates on Alden's life insurance policy. He meets his old friend, fire insurance agent Jim Parks, not knowing that in the need of money to help his ill wife Parks collaborates with arsonist Lucas Ives.
At the request of his friend Andy Spencer J.R. flies to Maui, Hawaii, and is immediately caught up in a nightmarish situation: At the meeting-place J. R. is found with a stabbed dope pusher and arrested for the crime. Believing his friend will help clear him, Andy is summoned to the police station, but Andy disavows him. Police Lt. Walt Abbott finds marijuana and money in J. R.'s bag, further incriminating him. Barnaby and Betty arrive in aid of the framed J.R., but due to an old grudge Abbott denies any help. In desperation, JR escapes from jail to try to solve the crime.
After escaping from prison, J.R. enlists the help of Andy's sister, Toni and tries to meet with Andy, but a trap has been set, and Andy is killed. Convinced that J.R. is innocent of her brother's murder, Toni takes J.R. to a small cabin on the property, where J.R. witnesses the harvesting of marijuana and realizes that Toni's older brother Michael is involved in the smuggling of drugs in pineapple boxes.
At the request of a former girlfriend in Chicago, J.R. tracks down her younger sister, Jennifer, who has run away to LA. While at a party, Jennifer makes a phone call from the bedroom and sees the drugged rock-star Randy March and the red dress belonging to March's dead girlfriend. Believing that Jennifer may have seen the dead woman, March's representatives try to track down the teen.
When a counselor at the Fresh Start drug rehab is killed under suspicious circumstances, J.R. goes undercover as his replacement to investigate. He uncovers evidence that another counselor and a student may have been involved, but his life is in placed in jeopardy when his vehicle is searched and the killers learn that he is a private detective.
Betty investigates as she cannot believe that her friend, theater agent Larry Collins, died from a heart attack while jogging. She finds out that Larry had an affair with his assistant Anita, but suddenly married actress Jessica. When colleague Krueger finds out about Anita's embezzlement, she kills him, and Jessica is the suspect.
During his investigations to find millionaire Kirkland's girl friend Ursula P.I. Gannus is shot, because he ""knows too much"". He asks his old friend Barnaby for help. Ursula steals items from Kirkland's art collection and her accomplice Nick smuggles them. Gannus wants to get a piece of the action by extortion.
Being on hustler heading unwittingly young Susan Cooper tries to hitch-hike, is mistaken for a prostitute and accidentally killed by judge David Kingsley. Susan's father asks Barnaby to clear her name. During his investigations Barnaby meets ""Chronicle"" reporter Walt Di Angelo, a friend of Kingsley's.
Judy Corbett works at Radburn School to help her autistic child Jimmy. This dedication ruined her marriage with Roy. Shortly before she can meet her friend Betty she is murdered. The only witness is Darlene, another autistic child. Betty tries to get access to Darlene's world to find out about the murderer.
When writer Al Geiger at Luxor Publishing Company reports incriminating evidence against Luxor's niece Jackie, Steve Webber suggests him to hire Barnaby. After meeting Barnaby Geiger is found dead. J.R. investigates and finds out that Ralph Luxor's business advisor Wells Thompson posed as ""Barnaby"".
Betty's cousin once removed, Donald Forest, asks her to investigate the death of his father, but before they can meet he is killed. William Tarkington IV and V, private detectives, think Betty is the prime suspect, who wants the inheritance of her great aunt Emily. When Betty is also threatened they change their mind.