Homicide detectives Ryan Walker, Nora Houghton and Lt. Ben Carroll try to close a string of strangulation murders. Carroll and his divorced wife, Bonnie, decide to stop sleeping together. She confides in him that she's seeing another man. Walker jeopardizes the investigation when he begins seeing a conniving television reporter.

Walker is assigned to head up a task force on the strangler. Nora's brother Jack steals information and leaks it to the reporter Holly Bennett after she seduces him. Bennett places herself in harm's way when she agrees to meet the strangler. When Nora and Walt are ambushed, Nora shoots the gunman in Chinatown shoot-out, but also inadvertantly shoots and wounds Walt. This prompts Nora to consider leaving the force.

Ben and Ryan team up with Theresa Baldoni, a tough New York cop, who comes to California to catch the man who murdered another cop; only she's not interested in justice, she wants revenge. Carroll becomes romantically involved with Baldoni. Nora and Walt protect a young girl orphaned after a hit man kills her mother.

As Walt prepares to retire, he looks into a 13-year-old murder case and learns he arrested the wrong man. The department throws Walt a going-away party. Ben teams Ryan with Nora. Ryan hopes to entice Nora romantically, as they investigate a suspicious suicide. Ryan and Nora uncover that the suicide was actually a murder with a dentist for the prime suspect.