A people-smuggling ring brings Nash and Joe to the aid of a young man searching for his parents.

Nash follows the trail of James and Lorraine, a thrill-seeking couple on a wild crime spree in San Francisco. Nash feels personally responsible for the fate of Lorraine when he discovers she is the daughter of a volatile SFPD Inspector. Nash's interaction with the young fugitive color his relations with Cassidy, who's semi-nude photo is splashed all over town in a racy safer sex poster.

Nash's old nemesis from the SIU, Rick Bettina, now a bounty hunter, is back and in competition with Nash as they both try to track down mobster Ray Goetz, who Bettina wants on assault and battery charges in Vegas, and Nash suspects of ""hitting"" a high-level mob boss. Meanwhile, Joe fears repercussions from Inger after losing his wedding ring.

Nash and Joe investigate several brutal drug-related gangland murders and follow a complicated trail of clues to a surprising suspect -- Bruce Sutcliffe, a multi-millionaire from a well-respected San Francisco family. When Nash discovers that Sutcliffe has been a major drug kingpin for years, he risks his job and his life to expose the magnate's secret life. Meanwhile, Evan and Bettina go undercover in a transgender beauty pageant to trap a blackmailing murderess who pretends to be a man impersonating a woman.

Jake Cage and Caitlin go undercover to capture an international fugitive returning home for the wedding of his daughter. Nash and Joe steal a violin for corporate clients, only to have the violin stolen again by one of Joe's detective students. Evan gets involved with a street prostitute.

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 must track down Rick Bettina, who escapes custody during his parole hearing, and recover the $2.5 million dollars in pension money he stole. Joe plays a modern-day Cyrano when the love affair between Dov and Amy abruptly ends, jeopardizing his remodel.

Nash is suspicious of a teen's involvement in a brutal ambush that targeted a pair of lawyers, leaving one riddled with bullets and the survivor barely wounded. Meanwhile, Joe is burdened by an unwanted roommate, and Cassidy begins seeing Rachel's blind date.

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.