Nash and Joe are on the trail of a Prowler who is terrorizing San Francisco and kills a member of Nash's S.I.U. team. When Nick springs for dinner at a Hawaiian restaurant, Joe's son J.J. chips his tooth on a piece of poi; Joe and Nick conspire to get a settlement from the restaurant.

Nash and company foil a jewelry heist ring posing as firemen. Nash hits a pedestrian and gets sued. But Caitlin has misplaced Nash's auto insurance bill, and he blames Caitlin.

Nash and Joe meet Lyle who tells them the secret location the SIU barge has been towed to. Joe returns Lyle's chihuahua Ginger who has been held hostage in return for the info. A truck deliberately rams into a van containing three prisoners. Nash and Joe arrive at the accident scene, with Nash figuring out that a phony paramedic van has taken the three prisoners in a successful escape attempt. Nash, Joe, Harvey and Evan arrive at the empty and disconnected SIU. The Mayor has granted a one week reprieve pending the Police Commission hearing. If Nash and company catch the three escaped prisoners, the SIU will be saved. Head of MCD Reuben Banks daughter Gina's immunity deal is also dependent upon the return of one of the escaped prisoners - Gina's former boyfriend, Jimmy ""Shank"" Brasher. The other two escapees are Darnell Galloway and Elliot Wong. Gina is kidnapped by Brasher. Jake Cage of Fugitive Recovery is already on the case, beating Nash to interview Mr. Footman, owner of the stolen

Evan puts himself under suspicion after he takes $40,000 of drug money during a bust; Nash and the SIU take down a drug dealer. Nash and Joe guard a chimpanzee, while Jake Cage goes undercover as an animal extremist.

Nash begins to believe that a 17-year-old boy involved in the Southeast Asian drug trade may be his missing brother's son; Cassidy starts dating a plastic surgeon and considers getting breast implants.

Hot on the trail of a murderous criminal from Chicago, Nash teams up with a KAREN DECKER, a cop from the Windy City who's in every way his equal: smart, competent-and yes, sexy. Sparks fly between them as they track down the visiting villain together -until, that is, Nash learns his newfound partner is not as perfect as she's led him to believe. Joe, meanwhile, hires a pet psychologist to cure what ails Nick's racehorse, Mr. Woody.

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.

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.

Nash discovers his life savings is gone when his accountant invests in a deal cooked up by "Bombshell" Tamara Van Zant. While trying to remodel the bathroom himself, Joe burns down his house and takes Nash up on his offer to move into Lisa's. Nick decides to take scuba lessons.

Nash must stop a sniper terrorizing the city by shooting victims at random. A rat infestation forces Joe to confront his ""landlord,"" Nash, about the problem. Evan proposes to Cassidy, but in the wake of a serious traffic accident, Cassidy is left fighting for her life.

Nash and Joe are plunged into the underground world of steroid-crazed body builders when they investigate the murders of three body builders. Nash and Caitlin struggle to define their relationship as Cassidy struggles to get her feet back on the ground after her accident.

Nash and the SIU must re-open a serial killer's case file when a body is discovered and it appears to be Angel's. Bonnie, Harvey's ex-wife, returns with an interesting proposition. Joe and Caitlin square off as rival soccer coaches when their teams enter the playoffs.

Handcuffed Skip Osaka jumps out the back of the moving 'Cuda. Nash and Joe give chase. Skip runs up a fire escape onto a power line. The line breaks, and Skip falls through a window. Nash and Joe place him in the trunk of the 'Cuda, and bring him to the SIU. A surprised Nash, Joe and Harvey discover the SIU barge is being towed away by a tugboat. The Head of the MCD, Reuben Banks, drives up and informs Nash the SIU has been temporarily shut down. The SIU is disbanded by MCD: Nash and Joe are assigned to Park Detail, Harvey to Homicide, Evan to Traffic, and Caitlin to Vice. At the Civic Center Park, Nash and Joe meet Colonel Culpepper, drug addict/transient, and Phil, the phony Vietnam veteran. The Colonel is shot dead in the park. Harvey and his new partner, Inspector Riley Webber, investigate the murder. Evan and Cassidy have set a wedding date. Harvey is best man, and he plans the bachelor party. Nash and Nick are informed, and Nash gives his blessing. Father Nick gives Cassidy her g

A juror becomes a vigilante avenging murder victims. Caitlin and Joe go in on a donut business venture. Evan is arrested and calls Cassidy; Cassidy finds a new boyfriend.

Wearing his brother's uniform as a motorcycle cop and impersonating a police officer, a deranged man imagines and talks to his dead brother. Nash adjusts to his break-up with Caitlin; Nick fails his driving test; Cassidy asks Evan for help to move back into a Berkeley apartment.

Nash goes undercover to stop a high-end heist artist. Joe helps a restaurant critic who receives death threats; Evan is back in the SIU; Caitlin takes an administrative job within the department; and Harvey helps out a troubled 12 year old boy.

Nash and Joe arrive in Las Vegas, and locate assassin Roy McNeer's hotel room. His food is still warm, as Nash and Joe spot McNeer in a casino. Nash and Joe give chase, but are held up by the hotel security guards, as McNeer escapes. Nash and Joe check into the hotel - Pepe is the concierge. They locate McNeer's girl, Vivienne Reed, and she agrees to tell Joe if McNeer calls her. The truck full of half a billion in laundered cash is hijacked. The two thugs contact Tony B to ransom the truck for $50,000. Tony B and the SIU meet them and get the truck back. Harvey, Evan, Officer Ronnie and Tony B go to Las Vegas with the truck full of money. Jake Cage shows up in Las Vegas too, with orders from Caitlin and the Mayor's Office to bring back Nash. But Jake agrees to help Nash instead after an altercation. Nash meets with Ellen Holiday. She fills Nash in on the rest of the DEA investigation. Jimmy Z works for a drug king pin coming in from Shanghai - they have ordered the hit on Police Chief

Nash's former lover Tamara Van Zant forges his name on a marriage license and claims to be married to him in order to protect herself from a thug out to kill her; Nick pretends to be romantically involved with a lesbian friend to deflect suspicion from the woman's son, a high-profile gangster from Philadelphia.

A serial killer who picks up passengers in a cab and then murders them stalks the city; Cassidy struggles with whether she wants to continue to be a cop.

Nash has to deal with the fact that Joe may have 72 hours to live after being exposed to a deadly virus while Nash & Joe investigate a drug theft from a research lab.

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.

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 and Joe are the targets of a bail bondsman, who bails out small time thugs and uses them as assassins. Nash and Joe also open up a new detective agency; Bridges & Dominguez - - their first case is finding the stolen wig of a Cher impersonator. Harvey and Evan's friendship is tested when Evan sells Harvey a faulty washing machine.

An innocent man is scheduled for an execution. Nash, working the entire case from the 'Cuda, must bring the true killer to justice before the midnight deadline. Lucia's bullying of a schoolmate forces Joe and Inger to attend conflict resolution therapy, which only leads to more conflict.

Nash finds himself defending Caitlin when she's the main suspect for a murdered CIA agent connected to her mysterious past. Joe begins working out with the trainer from hell. Cassidy and Nick enter a tango dance contest.