A female undercover agent for the DEA is raped and murdered, leading to a complicated investigation and the arrest of a suspect highly connected with a Colombian drug cartel. This is the toughest case of Cabot's career as she is faced with death threats on herself and her family along with pressure to yield the case to federal authorities.

A subway commuter is found castrated and bleeding profusely, leading the detectives to discover their "victim" may be the perpetrator in abducting women and forcing them to live in his dungeon for several years as his bride. As the detectives prepare to arrest their victim turned suspect, Benson arrives to find him murdered.

The conviction of a group of sociopathic high school bullies who turned on one of their own escalates into even more violence and death in their exclusive private school.

After a young woman is found raped and murdered near a nightclub with five hundred dollars stuffed into her mouth, Benson and Stabler follow the fingerprint trail on the money to Attorney Jason Whitaker, whose sole responsibility seems to be handling the trust for the Duvall family. Soon detectives are convinced that Gabriel Duvall is their rapist, but don't have quite enough evidence to put him away. ADA Novak is working on both the case and a terrified former victim when she is brutally attacked in her office late at night. The crossover continues on Law & Order: Trial by Jury S01:E11 Day (II).

Monica Phelps is found dead in her apartment, her son Nathan hiding in the closet behind her body. Detectives soon link Monica's death to philanthropist Ted Carthage, who runs an organization dedicated to helping people get off the streets. Benson is certain that Carthage is the killer, but a shaky ID from Nathan puts him back on the street. After Nathan kills Carthage himself, Sophie Devere argues that Nathan committed the killing because he saw Carthage shoot his mother -- something the gun manufacturers don't like.

Stabler teams up with an new partner to investigate a sexual attack on Jessica DeLay, a sixteen-year-old girl who worked tobacco stings for the Department of Health and face an overweight young brother and sister who claim it was an act of vengeance for Jessica and her friend, Tommy Strahan, beating up their older brother Rudi for being fat. Stabler and Blaine arrest DeLay and Strahan, but when the two are released due to lack of admissable evidence, Rudi Bixton takes justice into his own hands.

Stabler finds himself drawn into a case where a young mother has committed suicide after her baby goes missing. The case leads to questions for Benson about her own family history.

Stabler and Munch uncover a chastity club and a group of girls with a pregnancy pact at a high school where they came to investigate the death of a student.

When a pediatrician convicted of abusing patients is found dead, Stabler and Benson investigate and soon find ADA Cabot has a reason for becoming involved in the case.

One case becomes two as a murder leads to a serial rapist who is busy spreading disease along with his assaults, and the detectives' only clue is a website set up for casual and anonymous encounters.