A people-smuggling ring brings Nash and Joe to the aid of a young man searching for his parents, while Harvey is smitten with a woman he suspects of being a former ‘60s radical.
Nash and Joe find themselves having to solve a murder while fending off a trio of hit-men.
Nash gets stuck with an 11-year old delinquent who's the link to busting a drug kingpin.
After a nearly 20-year absence, the notorious San Francisco serial killer “Zodiac,” returns to taunt Nash and his mentor.
Joe is exposed to a deadly virus which could leave him only 72 hours to live as well as infect the city of San Francisco.
While investigating a judge's murder, Nash triggers an internal probe. But when the Internal Affairs cops go bad, only Nash and the SIU can stop them.
When a deadly anti-tank system disappears from the Presidio, Nash, aided by an attractive supply munitions officer, must find the weapon before it can be used for its final deadly purpose.
When a pension dispute forces Joe to rejoin the force, he and Nash team up to track down a nefarious heroin dealer.
While coming home from a late night bachelor party, Nash and the SIU team get caught up in a train heist gone bad, forcing them to overcome a hostage drama before time runs out.
Nash and the SIU unit are caught off guard when a group of rogue gangsters form an outlaw gang and terrorize Chinatown.
Nash tries to stop an insane ex-cop with a vendetta against the city from assassinating the Mayor.
Pressured in his personal life by his wife, who has filed for divorce, Nash goes undercover to break up a multi-million dollar bogus computer chip ring.
Nash goes undercover in Las Vegas to track down the Chief of Police killer and$500 million in missing drug money Caitlin bids adieu to Nash and Cassidy reveals her future plans to Evan.
Nash has to track down a cop impersonator on a rampage across the city.
Nash fends off hit-men hired by Frankie Dwyer, who has returned in hopes of killing Nash.
When a woman suspiciously falls to her death, it leads Nash into an investigation ofthe lives of the victim, her lover and both of their spouses.
Nash assumes the identity of a hit man to expose a drug war between two rival kingpins and corruption within the FBI and D.E.A.
Nash puts Caitlin undercover to stop a small-time thug from selling kidnapped Vietnamese women as slaves.
Nash and SIU investigate a crew specializing in ripping off other crews after pulling their jobs.
Nash tracks a vigilante hunting three murder suspects released on a technicality.