Seeking Hardcastle's help on a case of corrupt cops, a young patrolman is killed before he or Hardcastle can seek higher help in the department. With the case dealing with bad cops who could recognize the investigators, McCormick is asked to go undercover to flush out the corrupt cops and find the patrolman's killer.

In a change of pace episode, Mark begins to believe that Leprechauns are burying gold on the estate. Ignoring Mark's outrageous claims, Hardcastle concentrates on preparing the estate for an upcoming magazine contest. After Benny, Mark's mechanic, is assaulted by a group of men for information about a group of little people, Hardcastle admits that there may be some truth to Mark's Leprechaun story. That night, Mark and Hardcastle set a trap for the "Leprechauns". The trap works and Hardcastle captures the men who have been hanging around his estate. As the judge discovers, however, the little people are not Leprechauns but rather circus performers. Confronting the performers about why they are hiding out, Cluracan, the groups leader, explains that they are fleeing from communist agents that want to return them to their home country as well as Marvin, a circus promoter that had promised their services to Circus Maximus. As for the mysterious gold, Cluracan reveals that it is his family's money. The next day, communist agent Ivan and his men come to the estate disguised as employees of Ladies Garden Monthly, the magazine sponsoring the contest Hardcastle has entered. At the same time, Marvin and his men sneak onto the estate. With the circus performer's help, Hardcastle and McCormick manage to stop the agents as well as Marvin and his men. Later, Mark's continued suspicion that Cluracan's group are secretly Leprechauns seems to be confirmed when a rainbow leads to a mysteriously repaired Coyote.

Mark and Hardcastle take a group of misfit kids to a local prison in order to scare them straight; but while they are there, they are taken hostages by prisoners who are frustrated because of the repeated abuse from the guards and the warden.

Boxer Kid Calico is told to throw a fight in order to keep his kidnapped father alive.

Hardcastle visits a man he sent to prison for life only to find that the man never made it there.

While judging the Miss Sixteen beauty contest, Hardcastle becomes wrapped up in the life of car salesman Ed Whitman, the pageants grand marshal. Worried when her boyfriend Victor Hernandez reveals that his uncle disappeared while sneaking across the Mexican-United States border, Melissa Whitman, Ed's sixteen year old daughter and one of the pageant's contestants, goes to Hardcastle for help. Although Victor's uncle does eventually turn up alive, Hardcastle decides to find out what happened. With Victor's reluctant help, Hardcastle discovers that a man was murdered during a transfer of illegal immigrants across the border. Thanks to Victor, Hardcastle also learns that a lawyer named Antonio Morales, who claims no knowledge of the murder, has been helping to arrange illegal immigrations. Before the judge can get more information from Victor's uncle, the illegal immigrant is murdered. With Morales' help, Hardcastle goes undercover as a perspective immigrant. The judge's plan works and the illegal immigration ring is stopped. At the same time, Hardcastle discovers that Ed Whitman is the mastermind behind the illegal operation. Returning to the United States, Hardcastle and McCormick help the police take Whitman into custody. As the episode ends, Melissa loses the pageant to a girl named Sara Jane Rose.

Hardcastle & McCormick set out to assist a lawyer, who is an old friend of Hardcastle's, convict a mobster who is running stolen property in semi-trucks.

Mark surprises the judge when he not only qualifies for, but becomes a winner on, The 1 Million Dollar Trivia Master, a television game show. Unbeknownst to Mark, veteran game show producers Harry Baxter and Art Healy, envisioning big ratings, decide to help the ex-race car driver along once they discover that the audience is cheering for him to succeed. To guarantee a winning streak, the producers have Hardcastle's estate bugged and begin basing their questions on Mark's home practice sessions. Although Hardcastle quickly realizes that something is amiss, Mark is unwilling to accept that the game is rigged. After Diane Templeton, one of the trivia show's employees, dies under mysterious circumstances, Mark turns around and admits that something is seriously wrong. Searching the show's offices, Hardcastle finds out why Diane was killed: She had obtained a tape proving the show is fixed. Meanwhile, Baxter and Healy discover that Bryce Benson, the shows host, had taken their plan to a deadly conclusion by killing Diane. Not wanting to face murder charges, the producers decide to tell Hardcastle everything. During the taping of the show's final round, Mark, giving up his chance to be a big winner, reluctantly helps the police stop Benson. Hinting at the series eventual conclusion, Mark jokes about going to law school in this episode.

Hardcastle is quite upset when he is criticized in “Without Sin,” the autobiography of retired mobster Joseph Cadillac. Figuring that the mob, also the subject of Cadillac's criticism, will be angered as well, Hardcastle has Mark follow the author. Later, Hardcastle is surprised when Cadillac comes to him for help.

Robert Culp guest stars as Arthur Farnel, an ex-con who runs a school leading and teaching their students how to break the law. Mark decides to go undercover in order to gather enough evidence to put him away.

Hardcastle & McCormick go undercover at a computerized dating service in order to find out why wealthy clients are turning up dead.

Jesse Wingo, the former famous singer, is spotted by McCormick at a talent contest. But when approached about his past, the contestant reveals his name to be Sam Jones. Puzzled at the similarities, Mark investigates the man only to find that other people are looking for the man named Sam Jones, but want him dead.

Questioning his maturity, Mark decides to trade in the Coyote for a more conservative car. To his surprise, his credit application is rejected due to an $18,000 default. Investigating, Mark discovers that his name was used in a real estate deal put together by Melinda Marshall, the girlfriend that had helped put him in prison. (As revealed in a flashback sequence, Mark, having foolishly placed his car in Melinda's name for insurance purposes, was arrested for stealing his own car.) Hoping to clear his credit record, Mark pays a visit on Melinda. Confronted by Mark, Melinda reveals that she had faked the real estate contract in order to win a car. When someone tries to steal the car Melinda won, Hardcastle realizes that there is something more going on than a simple real estate deal. Hearing that Melinda works for Ted Rubin, a man in his files, Hardcastle realizes that the real estate company is running a land fraud scram. Realizing that there is probably something hidden in Melinda's car, Hardcastle and McCormick conduct a search. As a result, they discover valuable stamps in the car and learn how Rubin has been transferring his money. Although Rubin arrives at the estate ready for a fight, he is captured thanks to the timely intervention of the FBI agents that had been investigating him. [During this episode, both Mark and Hardcastle have extremely subjective recollections of Mark's original trial.

A gang member is remanded into the judge's custody only to stay in the guest house with Mark, while the judge and Mark go after a psychiatrist who has been taping private sessions with clients revealing vital damaging information.

Mark is thrilled when he gets a shot at racing in big leagues—only to learn that his sponsor's auto parts business gets their inventory from stolen cars.

A group of retired judges decide to take the law into their own hands by delivering their own verdicts to criminals who slipped through the system or were given lesser sentences based on technicalities or lack of evidence.

After breaking into the official records, Mark identifies his long-lost biological father as a lounge singer in Atlantic City and goes to see him. But the man turns out to be sought by a mobster who kidnaps Mark to force him to steal some incriminating tapes from a government safe.

After finding his sister-in-law missing and her apartment ransacked, Hardcastle discovers that she had been secretly following her professor in hopes of earning extra credit in a police procedures course.

A critically-wounded criminal admits to being paid to frame a former baseball player, Duke McGuire, for murder. Feeling responsible for his false incarceration since he was the presiding judge, Hardcastle tries to help McGuire become a baseball player once again. But his attempt at a comeback is threatened when drugs are found in his locker.

Innocently given a friendly kiss by a woman named Aleeya "Ali" Casir, Mark unwittingly falls into the middle of a major international incident: Assuming that Mark is the American his daughter has been living with, Sheik Abdullah Casir, Ali's father and the leader of an oil rich mid-eastern country, decides to take whatever steps are necessary to protect his son's honor. As a result, Casir orders his Americanized daughter to marry Mark. Meanwhile, Hassan and Rabin, Casir's sons, begin to set up a drug dealing operation. Hoping to maintain friendly relations with Casir, the State department approaches Mark and "requests" that he marry Ali. Although Hardcastle tries to explain to Casir that Biff Anderson, Ali's real boyfriend, would be more than willing to take Mark's place, Casir, having already made an official announcement, is unwilling to change his plans. Forced to follow through with the wedding, Hardcastle, having learned about Casir's drug dealing sons, decides to use the ceremony as an opportunity to expose Hassan and Rabin. Confronted with his sons' guilt, an angered Casir vows to spare himself grief by staying out of his children's lives. As such, the wedding is canceled. Later, Mark is amused to hear that Ali has left Biff to marry a 35 year old television executive.

Cleaning out his shed, Hardcastle comes across an old trophy belonging to Teddy Hendrix, his college roommate. Deciding to visit Teddy, who is now a basketball coach, Hardcastle walks into an attempted kidnapping. Since Teddy flees the scene before he has a chance to confront him, the judge visits his old friend's wife. Thanks to Fran Hendrix, Hardcastle discovers that Teddy has been having a disagreement with a man named Roy Barlow. Realizing that his best chance of solving his problems lays with the judge, Teddy decides to tell Hardcastle about how he has been fixing basketball games. Agreeing to help his friend come clean, Hardcastle arranges a meeting between Teddy and the district attorney's office. Before Teddy can testify, Fran, who has secretly joined forces with Barlow, lures her husband into a trap. Meanwhile, Fran also helps Barlow capture Hardcastle. Thanks to Mark and their old basketball team buddies, Hardcastle and Teddy are rescued. Additionally, Mark and the former team members capture Fran and Barlow.

Hardcastle & McCormick travel to Rio to track down a drug runner.

Mark attends the funeral of an old friend, only to be surprised later to receive a message from her on his answering machine. After searching for evidence to her supposed "death," Mark and the judge find political reasons may be to blame for her disappearance.

Mark is thrilled when he wins $20,000 racing in the Arizona Modified. His joy quickly dissipates when thieves hold him up and steal his winnings as well as the Coyote. Based on Hardcastle and McCormick's description of the thieves, Deputy Sheriff Dan Johnson realizes that they were robbed by locals Arvin Lee and Melissa Kantwell. Complicating matters is the fact that Melissa is the wife of Billy Blackstone, the city's sheriff. After recovering the Coyote from a used car salesman, Hardcastle and McCormick begin to track the crooks. To their surprise, they catch up with Arvin Lee only to discover that he has been murdered. Putting the pieces together, they realize that Blackstone probably killed Arvin Lee. Taking their theory one step further, Hardcastle and McCormick speculate that Melissa only pretended to fall in love with Arvin Lee in order to trick him into stealing for her. With Johnson's help, the judge and Mark locate Blackstone and Melissa. With Blackstone unwilling to surrender, the deputies are forced to shoot and kill him. To Mark's regret, the shoot-out starts a fire that destroys his racing winnings.

Although Hardcastle is initially pleased to be invited to a party on a private train, his emotion changes to anger when he discovers that he has been lured onto the train under false pretenses. His ire is further raised upon discovering that the train is not scheduled to stop for another day. One small consolation: Mark, accidentally trapped on board the train, is around to help him find out what is going on with the trip. The mystery takes a deadly turn when one of the passengers is murdered. Although the unknown murderer temporarily manages to get rid of Mark by throwing him off the train, the ex-race car driver, who is unable to identify his assailant, pools his resources and returns to the train down the track. Another murder prompts Hardcastle to set a trap for the killer. While Hardcastle pretends to be a victim, Mark purposely lets slip that the judge had obtained evidence against the killer. Taking the bait, passenger Carl Sharples tries to search Hardcastle's "body". Exposed as the killer, Carl reveals that he has been eliminating the people (strict teacher, ex-girlfriend, army commander, high school coach, that he selfishly believes "ruined" his life. With Mark's help, Hardcastle stops Carl before he can hurt anyone else.