Nash is undercover in Las Vegas to stop an Asian kingpin; Evan is shot in the line of duty; Cassidy plans to attend the police academy.

The Chief of Police is assassinated, and a money-laundering operation is set up between San Francisco and Las Vegas. A rogue DEA agent and the assassin are after a half-billion dollars in cash, and Nash and Joe follow them to Las Vegas. Nash locates Angel's lost wings and gets Nick a cell phone.

A nurse who assists a plastic surgeon for the mob is murdered because she stole the before and after photos of altered mobsters. She passes a key to the hidden files to Joe, and Joe becomes a target of a mobster. Nick appears with Cassidy in her play, but suffers a bout of Alzheimer's. Harvey meets a new girl, but she is a former lesbian.

A gang of female prisoners escape in search of five million dollars in bearer bonds, while Nash helps the woman framed for the theft of the bonds. Joe has trouble with a delivery boy, while Cassidy considers a career with the CIA.

Nash goes undercover to bring down an international thief out to steal top-secret government computer chips; Evan returns to the force; Caitlin considers a promotion that would make her Nash's boss; a restaurant critic hires Joe to find out who's threatening to kill him.

Two drug dealers are gunned down outside of a ritzy restaurant and a pregnant 18-year-old street kid is the only witness, or so she claims; Evan and Cassidy are caught in an embarrassing situation; Nick and Joe get involved in a scam.

Nash searches for a robber who disguises himself as a uniformed police officer; Joe gives Nick a driving lesson; Caitlin moves her things out of Nash's apartment; and Evan helps Cassidy move back on campus.

Nash and Joe barely escape an explosion that rips through a nearly vacant office building where they hired on as security consultants. Meanwhile, Nick becomes interested in Joe's mother-in-law and Evan gets baptized.

Nash looks into the death of a woman who fell eight stories from a hotel balcony. Meanwhile, Joe invites Evan to live with him, after Evan is beaten up by a pimp. Boz Bishop asks for a promotion at the detective agency.

To flush out a drug lord, Nash goes undercover posing as a hit man. Meanwhile, Nick tries to talk his poker buddies out of robbing a bank, and Inger and Lucia come back home to Joe after five months of being away.

Lowlife Frankie Dwyer returns, this time importing Vietnamese women as sex slaves, as Caitlin goes undercover as the seller. Nash has a tooth ache and refers to Caitlin by his first wife's name. Joe is aggressively pursued by bodybuilder Spike; Evan bumps into Cassidy in his job as a parking lot attendant.

Nash nabs a thief who was himself ripped off by a gang of robbers just after he pulled a heist at a rare coin store; a father hires Joe to find out what happened to his missing son who was supposedly kidnapped five years ago; someone spray paints Nash's car.

Nash and the team track down a vigilante intent on bringing murderers to justice; Caitlin and Joe form a partnership to deliver doughnuts via the Internet. Evan gets in trouble and calls Cassidy for help. Cassidy finds a new boyfriend.

A paranoid man, who believes someone is out to kill him, randomly kills people while they use cellular phones; Nash and Joe aid a ventriloquist who receives threatening calls; Joe wrestles with disturbing dreams; and Evan runs into trouble on his new job.

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.

An ex-con claims to suffer from multiple personalities when he is caught robbing banks; Nick moves to a high class retirement home to meet a rich woman; Harvey confronts Evan about his substance abuse.

The twin brother of the city's pension fund administrator informs Nash and Joe that his sibling stole $5 million from the fund. Meanwhile, Bettina is fired when his zeal to become city supervisor goes too far; and Nash and Caitlin try to get away on a vacation to Jamaica.

Nash persuades Jake Cage to help him trap a fugitive at a high society wedding, but first Caitlin must give Cage a lesson in proper etiquette. Meanwhile, Nash and Joe steal a Stradivarius violin to test a wealthy man's security system.

Nash must figure out why two thugs tried to kidnap Cassidy outside of her new apartment right in front of his eyes. Meanwhile, Joe becomes involved with a woman through e-mail and decides to meet her.

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 company foil a failing restaurateur's kidnap plan to ransom his nanny's child. Nick has sex with Bridget, Caitlin's inept maid. Inger returns for a visit, but leaves for Sweden again. Cassidy has a friend attempt suicide because he can't get a date with her.

At a movie premiere, an actress is murdered in front of a crowd of fans that includes Nash. Meanwhile, Caitlin moves in with Nash, and Evan returns to the force.