Season 4

When a lady cop is killed in a drug sting gone wrong, her boyfriend cop decides to take matters into his own hands. Stone and Keller try to stop him.

While a psychopathic killer uses San Francisco hi-rises as target practice, Stone and Keller have to contend with a new Captain who immediately countermands everything they do.

Prison gangs intimidate weaker prisoners into having their wives smuggle drugs into prison -- and kill the wives if they don't.

A rapist targets Stone's daughter and her friend; a radical feminist organization encourages them to take matters into their own hands.

A retired history teacher goes off the deep end and takes it upon himself to take a group of his former students hostage in an empty, condemned school. There, at gunpoint, he proceeds to teach them the finer points of history.

After Stone is hit by a van and suffers an inner ear injury, he considers changing to a desk job. Meanwhile, the vengeful wife of a man he killed stalks and tries to kill him in his half-deaf state.

Property owners who refuse to sell their parcels find themselves murder victims at the hands of a developer.

When a gang of smuggling sailors kills a jeweler, they realize they have to eliminate his girlfriend for being a witness, and Keller, who is transporting the girlfriend to jail.

Keller and Stone's sole witness in a jewel robbery turns out to be a compulsive liar.

A sleazy radio host is accused of murder when a former girlfriend, who was pregnant, is shot.

A youth-center worker is caught in a war between two teenaged street gangs, a war that really has the heat turned up when one of the gangs obtains automatic rifles.

Lieutenant Stone is placed in the awkward position of investigating a burglary with Irene Martin, a lady cop -- who is also his girlfriend who he's just proposed to. She resents his intrusion into 'her' case and their relationship unravels.

The death of a night-watchman during a burglary puts Stone and Keller into the midst of a spy-vs.-spy conflict between high-tech industrial espionage firms.

A teacher is murdered at an exclusive all-boys prep school.

A vigilante is methodically and savagely wiping out criminals who have managed to slip through the fingers of the legal system.

Stone and Keller search for the only eyewitness to a shooting -- a self-proclaimed doctor who gave them a false name.

A bishop (Mike's friend) tries to protect the person who shot him, but revelations in the course of the investigation start to shed suspicion on the bishop's accounting of events entirely.

A cop seeks to catch his brother's murderer by going undercover in an illegal gambling operation.

Four judges have been murdered, and in each case an obsolete pamphlet on disbarrment proceedings is found near the body...

Two retired brothers, both having worked as riggers for circuses many years before, are found murdered while a circus happens to be performing in San Francisco at the Cow Palace.

Stone clashes with an abrasive NYC cop who is on the trail of his partner's killer.

When an Immigration raid goes wrong and a security guard is killed, the prime suspect becomes one of the illegal immigrants.

Stone searches for a fugitive, and is dogged by the fugitive's innocent and naive daughter.