Nash and Joe help FBI Special Agent Katz recover a Suburban full of stolen FBI weapons. Joes sets Nash up on a blind date with his nanny.
Willie Nelson plays Earl Dobbs, a convict who gets a furlough from San Quentin to help Nash and Joe catch his former crime partner.
Nash and Joe track down a former mob underboss who's murdering San Francisco criminals. Meanwhile, Inger has to go out of town, leaving Nash and Joe with the baby.
Nash and Joe follow the trail of a criminally insane mental patient who believes he is the nemesis of Sherlock Holmes. Joe hires a baby nurse who takes over his life.
Nash, on the verge of closing a case, narrowly avoids getting killed in an explosion, losing a week's worth of memory as a result. With Joe's help, he has to retrace his steps, resolve the case, and deal with the various personal snafus resulting from his memory loss. Michelle joins the SIU.
Cassidy finds herself in the middle of an SIU case when she becomes the victim of a high-climbing jewel thief and Nash begins to close in on the suspect: her new boyfriend. Stacy becomes concerned that Nick is being turned into a lab rat at the university where he has volunteered for a research study.
A sniper terrorizes San Francisco on Halloween as a city-wide Blue Flu forces our SIU detectives to assume beat cop responsibilities. Joe tracks down a hard to find Halloween costume for Lucia.
When a reporter is murdered while covering the new ""French Connection"", Nash comes face-to-face with a startling revelation - his brother, a Vietnam MIA, thought dead for the last 24 years, may be alive and in San Francisco. Meanwhile, Lisa's sister, Lynette, arrives to house-sit at Lisa's indefinitely.
A fugitive is released from prison by mistake and seeks revenge on Michelle. Nash teams with Michelle to capture him. Meanwhile, Nash refuses to partner with Joe on an off duty case to protect a sportscaster being blackmailed, so Joe chooses Evan.
Sultry criminal and Nash's ex-girlfriend Tamara VanZant resurfaces, this time as a player in a plot to sell stolen plutonium. Joe plans to make a mint by marketing a secret-recipe salsa that's been in his family for generations. Robert Rodriguez stars as Joe's commercial director.
Rick Bettina returns as the head of the S.I.U. Joe is accused of stealing 3 million dollars from a suspect. Harvey has a torrid affair with a woman he once arrested.
Nash and Joe risk causing an international incident after British consulate workers fake the death of a convicted killer in order to use him for their own nefarious purposes. Joe resorts to extreme measures in order to get Lucia accepted into an ultra-elite school.
A million dollar bounty on Nash's head triggers an onslaught of attacks by a series of ultimate fighters. Michelle meets ""Mr. Right"" while on a stake out trying to trackdown an Internet rapist. Nash is convinced Cassidy's new boyfriend in gay.
Geraldo Rivera comes to the SIU to interview Nash and Joe. Nash arrives at the SIU after having his drink spiked with acid by a biker couple; and there's a ""mole"" in the SIU feeding sensitive information about Nash to Geraldo, which he uses in the interview. Meanwhile, our SIU cops must solve a mystery which begins as a routine shooting at a convenience store.
Nash is forced to take time off by Bettina.
Nash and Joe team up with a tough-talking NYPD Special Crimes Detective (Penny Marshall) in order to track down a famous fashion model's deadly stalker. Meanwhile, Harvey helps Evan track down his lost badge before Nash finds out. A shopping trip doesn't turn out the way Nick and Lynette had planned.
Nash gets involved with Irish terrorists, as well as his ex-wife Kelly (Serena Scott Thomas). Meanwhile, Joe looks after a party-minded Arabian prince awaiting a heart transplant.
Bettina is accused of killing a high-class call girl. Only Nash can help Rick find out who framed him for murder. Meanwhile, a man masquerading as Joe has become a major romantic figure in town (with Joe's credit cards), much to Inger's chagrin.
Nash and Joe are on the trail of a ruthless gang of thieves threatening to release the lethal nerve gas over downtown San Francisco unless the area is evacuated. Once the area is cleared of people, the criminals plan to move in and rob the banks in the area. Racing against time to capture the criminal mastermind behind this scheme, Nash is surprised to discover that the gang leader is Pamela Smith, a beautiful, brilliant chemist who created the deadly gas. Meanwhile, a mysterious woman appears who claims to be Joe's daughter from a college fertility experiment in which he participated years earlier.
Nash must protect Lynette (Suki Kaiser) from ruthless Hong Kong mobsters when she unknowingly becomes involved in an Asian forgery ring. When Lynette's old flame, Brian, mails her a flawless forgery plate for $100 bills, Nash must protect her from the brutal Hong Kong gangsters from whom the plate was stolen. When Brian unexpectedly appears at Lynette's door, their attraction is re-ignited, but he soon becomes the chief suspect in Nash's investigation into the forgery ring, run by an Asian crime syndicate. Meanwhile, Joe's visiting father (Ismael Carlo), a sheriff from New Mexico, drives Joe crazy with his meddling until he uses his own brand of Wild West sleuthing to expose a murderer in Joe's apartment building.
When Nash and Joe investigate the mysterious disappearance of several armored cars and their drivers, they uncover a high-tech, covert crime operation run by ex-Navy Seals. When the robbers kidnap Evan, Nash must lure them out of hiding by staging an armored car delivery. Meanwhile, an off-duty case finds Nash and Joe searching for a star football player's dream girl, whom he spotted in a stadium filled with 65,000 fans but doesn't know. Also, the relationship between Evan and Cassidy intensifies as they struggle to keep their affair a secret from Nash.
When the ruthless high school dropouts go on the crime spree, Nash's search for the couple leads him into an underworld of heavy metal rock and satanic worship. As the intensity of the crimes increases, Nash must race against time to stop the desperate duo before they murder all the enemies on their ""grudge list."" ; Stacy and Nash meet Nick's long-lost love from the war years; Joe finds Evan and Cassidy in a compromising situation.