More than $2 million worth of computer chips are stolen, causing Nash to go undercover to bust the thieves before the chips are sold to the Chinese military.
When Nash becomes embroiled in a violent gang responsible for a string of deadly home invasions, he and his family become the crew's newest targets.
Nash and Joe must keep a dangerous drug lord from invading the San Francisco heroin trade, so they set out to manipulate the man's partner and pit the two against each other.
The Mayor recieves a disturbing bomb threat, forcing Nash to track down both the device and the crazed criminal responsible - before time runs out.
After the Army's anti-tank system, "The Javelin," goes missing, Nash and his team discover a startling connection between the missing equipment and a string of recent gang violence.
While attempting a risky undercover purchase from some deadly Russian gangster, Inspector Harvey Leek is kidnapped, along with a suitcase full of money, and it's up to Nash and Joe to rescue him.
When a gambling boss is killed by his subordinate lover, a chain reaction of events begins. His valuable book of clients is sought after by a Rouge FBI Agent who was his former hitman, as well as a record producer with a penchant for injuring those who fail to produce in their music career. Nash is brought into the scheme just as he is supposed to leave for a vacation with Kelly, but his involvement is further complicated when Kelly's brother, a struggling musician who owes the record producer money, becomes involved in the chase for the book.
Nash's ex-wife Lisa is an eyewitness to a brutal murder, but when the victim's body goes missing, Nash must help her gather enough evidence to catch the killer.
When Nash shoots a criminal with whom he has a past, the Internal Affairs office begins an investigation. But after being questioned, Nash smells a set up and must find the connection between a crooked cop and his situation before he ends up locked up. Meanwhile Cassidy tags along with Evan and Harvey to try to catch a serial car thief.
A thief has broken into a lab in the city and stolen a highly contagious and deadly virus. What is worse, he has taken all of the antidote as well and because of it, the entire city could be in danger. Nash and Joe, along with the FBI, are pressured to find him before he can infect anyone else. Meanwhile, Nick decides to get married - on a days notice; and Lisa enters a very prestigious cake competition.
The leader of a Neo-Federalist group has been busted out of prison by the rest of his group and he has a vendetta for Nash who helped put him away. He wants his daughter back who has been put in witness protection. To even the playing field, he takes something of Nash's which forces Nash to play by his rules...
A group of criminals hits a bank in downtown San Francisco and Evan is injured in the process. With a leader who blends into normal society, the gang is hard to predict. In an effort to get justice for Evan, Nash and Joe try to stop the group before they can continue to terrorize the city. As a side project, they try to hunt down an old car that is lucky to the San Francisco Giants star player.
Things get personal for Nash when his former best friend turned international hitman shows up in San Francisco for a job. Intent on stopping him before he completes the job, Nash and A.J. must be on their A-game as they have never faced an enemy the likes or caliber of this one. Meanwhile, Evan endangers a mission to capture a long standing fugitive by trying to squeeze in a date with a woman who thinks he is someone else.
While re-acquainting himself with Kelly, Nash finds a crossing between his personal life and his current case of finding out who is responsible for two murders inside a prominent but shady family in the city. When it seems Nash has found the link he needs, his case takes a new twist and he and Joe must find out who is behind the murders before someone close to Nash gets hurt too.
Nash, Joe, Harv and Eve, one of Nash's acquaintances, are held hostage on a subway after a night out on the town. Their captors are led by a young and crazy female who is smarter than she appears. If her demands of ransom aren't met in one hour, then passengers on the Subway will begin to disappear... Meanwhile, Cassidy has to go to the ER in the middle of the night for stomach troubles.
When Nash is brought back to an old murder scene in a new case, he thinks he is on the trail of a notorious killer known as the Zodiac. Whether or not this current killer is a copy cat is up for debate, but regardless, he is lethal and the SFPD must take him down before his murders continue.
When Nash busts a twelve year old who is caught up in a drug ring, he attempts to show the boy the error of his ways. Stubborn as he is, he resists and leads Nash on a pursuit to protect him before the drug lord can find him. On the side, Joe struggles to help his son J.J. with a job while his wife is hounding him about selling the bar.
Nash responds to a robbery where an old partner of his has a personal interest - his daughter is being held hostage. After some investigating, Nash has to inform the old friend that his daughter is not a hostage, but an accomplice helping her boyfriend escape the country.
A hot shot female detective shows up from Chicago to help out on a case that originated in her city involving a big time dealer attempting to escape the country. But this detective may have alterior motives... Meanwhile Joe and Nick run into a problem with a new thoroughbred they have purchased.
A battle for power between two mob right hand men after the murder of their boss leads to an ugly span of crimes as they try to take each other down. It's up to Nash to bring them both to justice before they take each other - and innocent victims, out.
An old mentor in Chinatown is gunned down by the Triads under the direction of their new young and ruthless leader. To add to Nash's problems, an old friend of his with a gambling debt to make good on comes to him for help. When the two issues become intertwined, Nash has to take down the Triads and end his friends troubles while facing two seperate enemies.
Nash encounters a group of hired ex-military commandos who are working as a security force in a local project riddled with drug dealers. But when dealers continue to show up dead, Nash suspects they may be executioners rather than saviors.
Nash and Joe help a special agent recover a van loaded with stolen FBI weapons.
A prison inmate is furloughed to help Nash and Joe capture his former partner in crime.
An ex-mobster embarks on a murder spree and only Nash and Joe can stop him.
Nash and Joe pursue a criminally insane mental patient who believes he's Sherlock Holmes' archenemy.
An explosion robs Nash of his short-term memory, putting an important undercover operation in jeopardy.
Nash pursues a jewelry thief who stole a $5 million necklace from a penthouse apartment before parachuting to safety.
A police strike forces Nash and Joe back into uniform just as a rooftop sniper begins his reign of terror.
A reporter's murder leads Nash to believe his long-presumed dead brother is not only alive but also living in San Francisco.
An escaped murderer plans to kill the person he holds responsible for his conviction: the SIU's newest team member, Michelle Chan.
Nash's shady ex-girlfriend Tamara Van Zant returns to San Francisco, where she plans to sell a suitcase full of stolen plutonium.
The new head of the SIU suspects Joe of stealing millions of dollars from a money-laundering operation.
Nash and Joe risk an international incident when a murder investigation takes them inside the British Consulate.
A convicted arsonist offers a million-dollar bounty to anyone who succeeds in murdering Nash.
A biker couple spike Nash's drink with LSD just before he's scheduled to be interviewed by Geraldo Rivera.
Nash is forced off the job when he's ordered to take ten months and thirteen days of unused vacation time.
Nash and Joe joins forces with a no-nonsense NYPD detective to catch a murderer who's stalking a famous fashion model.
Nash's ex-wife Kelly becomes tangled up in a case involving an Irish terrorist who plans to kill an Archbishop.
When Nash discovers a member of a prominent San Francisco family is a major drug dealer, he risks his life to expose him.
When the head of the SIU is accused of murdering a call girl, Nash sets out to find the real killer.
A gang of thieves threatens to release deadly nerve gas in downtown San Francisco as part of a scheme to rob the area's banks.
Nash attempts to protect an innocent woman from Hong Kong gangsters after she unwittingly becomes involved in an Asian forgery ring.
When several armored cars and their drivers mysteriously disappear, Nash and Joe's investigation uncovers a hi-tech crime operation run by ex-Navy Seals.
Two teenage death-metal rockers go on a killing spree that leads Nash into San Francisco's Satanic underground.
When a hitman is out to kill an FBI Agent, but misses, Nash and Joe put him into protective services. Unsure who he is working for, they follow a path of foreigners, eventually to a submarine buyer. At the same time, Nash must deal with Lisa when she returns to tell him she is getting married - but can't yet because their divorce has never been finalized.