As friction grows in the wake of increasing deaths, Schibetta, Saïd, and Keane are brought together by Glynn, who tells them to keep their respective groups quiet or else he'll lock the prison down. The tension increases following a visit from Governor Devlin, who was responsible for the ban on smoking and conjugal visits.

Governor Devlin has reinstated capital punishment in the state, and the first Oz prisoner scheduled to die is Keane.

With Schibetta and the prison brass in a race to uncover Ortolani's killer (for very different reasons), we see how inmates react to visits from both their wives and, in one case, family members who are also in prison.

A recovered Saïd ostracizes Mershah for turning his back on him when he was dying—and orders the rest of the Muslims to do the same. Impressed by Saïd's power, Groves makes a deadly decision in his honor. Meanwhile, Beecher, transformed by prison life, finally gets revenge on Schillinger.

In the "Emerald City" experimental unit of Oswald State Penitentiary, we meet some of the diverse inmates who live within a pecking order of Homeboys, Latinos, Muslims, Irish, Aryans, and Wiseguys. No clear-cut leader emerges—with the possible exception of Kareem Saïd, a Muslim author who preaches non-violence and abstinence. Saïd's arrival doesn't prevent a short-fused Mafia inmate named Dino Ortolani from ticking off just about everybody—a habit that ends up burning him.

The infiltration of drugs into Oz has reached unprecedented levels, and the undercover efforts of McManus and Glynn to find out who's smuggling them in backfires in a deadly way. Despite a lockdown in Emerald City, the drugs continue to trickle in—and the blame shifts from prisoners to corrupt officials.

Beecher is released from the hole and Schillinger is left eyeless and weak. A riot breaks out after two white punks get into a fight over checkers. Frustration, sexuality, hate, revenge, racism all rear their ugly heads, causing the violence to escalate.

At the bi-annual review of solitary prisoners, the board decides to release Alvarez and Schillinger back into gen pop. Rebadow, still mourning the loss of his grandson, gets transferred to work in the library, where he is thrilled to meet the new librarian, Stella Coffo. Meanwhile, Timmy Kirk, now sentenced to Death Row, pleads to Father Mukada to help exorcize him; Ryan O'Reily seeks to prove his brother Cyril had no premeditated plans of murder; and Winthrop makes Schillinger an offer he can't refuse.

Ten months after the riot, Em City re-opens. A recovered McManus creates a council of group representatives to keep order, and initiates GED classes to help inmates get high-school equivalency diplomas. Having been told by O'Reily that Adebisi was responsible for his father's death, Peter Schibetta takes over the kitchen by cashing in a favor Glynn owes the family. As Schillinger's parole hearing nears, Beecher taunts his nemesis mercilessly in an attempt to ruin Schillinger's quest for freedom. Glynn's duaghter is raped by a group of Latinos, and the warden takes out his frustations on Alvarez. O'Reily learns he may have breast cancer.

Alvarez knows who raped Glynn's daughter, but refuses to tell the warden. Wangler is making progress at school, but his cellmate, Adebisi, isn't a fan of higher education. When Augustus Hill's judge is convicted of accepting bribes, Said takes up Hill's case to get him a second trial. Diagnosed with cancer, O'Reily goes to a hospital to get a prison-paid lumpectomy, which is cheaper than a mastectomy. The Aryans are losing credibility in Oz, so Schillinger arranges to have a tough named Vogel killed with Beecher being the next on the hit list. Finally, the prison is filled with excitement as a woman, Shirley Bellinger, arrives on death row to be executed.

Augustus Hill's court appeal is denied, despite the efforts of Said, who has better luck getting Poet's poems published. Meanwhile, O'Reily survives his lumpectomy, and now focuses his attention on Dr. Nathan. Trying to cut a deal after killing an Aryan inmate, Richie Hanlon is forced instead to admit to a murder he didn't commit. Schibetta offers Alvarez a piece of his drug biz in exchange for killing Adebisi. Beecher is forced to meet with the judge who sentenced him; it appears she has a guilty conscience. Beecher's new roommate, Chris Keller, seems to hate Aryans as much as Beecher but appearances can be misleading.

Alvarez and Guerra come up with a new way to settle their beef -- Guerra will stab Alvarez in the shoulder without killing him. Morales questions Guerra's decision to do this while he attempts to grieve for his sister. Rebadow gets more bad news about his grandson which prompts him to search for alternatives. Montgomery asks for more hush money from Ryan so Ryan devises a plan to have Montgomery eliminated. Officer Brass returns to Oz to get facts on who attacked him. Ellie O'Connor arrives as the Governor's liaison to Oz only past memories of her failed marriage to McManus return. Schibetta returns and Schillinger shanks Pancamo after learning that he had Hank killed. McManus makes an offer to Said and White to hopefully curb White's erratic and sometimes bizarre behavior. Ryan's mom, Suzanne Fitzgerald comes to Oz to instruct inmates in performance arts.

Glynn receives some good and bad news on the toxic-poisoning case. Meanwhile, Rebadow's relationship with Stella hits a snag; Keller and Beecher work out a mutually beneficial arrangement; Poet and Redding nearly come to blows; Hoyt is transferred from Death Row; and Robson finally gets some redemption.

Everyone has a different opinion of new inmate Idzik; Alvarez receives shocking news; Redding's attempts at reform continue; Murphy makes a confession to Glynn; Morales'(David Zayas) medical suspicions are confirmed; and Beecher's devotion to Keller leads him into a perilous position.

In the aftermath of the riot that killed six inmates and two officers, Oz is locked down, and Emerald City prisoners are sent either to solitary or "gen pop." A special committee is appointed to investigate the riot and Governor Devlin's handling of it. The committee's leader is law-school Dean Alvah Case, who roams Oz questioning inmates and officers alike. Inside a gen-pop prisoner named James Robson demands that Beecher perform oral sex on him, and gets a painful tip in return. Case determines that the death of inmate Scott Ross during the riot was no accident-but is the truth better left untold?

With their enmity at a boiling point, Adebisi poisons Schibetta -- but not fatally. Now that his brother has turned himself in for murder, Glynn no longer owes Schibetta any favors. Sister Peter Marie figures out that Giles witnessed who killed her husband. Poet, now a published author, gets his parole, but Governor Devlin still takes away funds from McManus's high-school equivalency program. When Beecher learns his wife committed suicide, Keller offers comfort, but his advances are rebuked. Meanwhile O'Reily is in love with Dr. Nathan, and gets his brother Cyril to have her husband killed.

Schilinger enlists Said to get him out of jail, but Said backs out. McManus decides not to incriminate Wittlesey in Ross's death. A recovered Schibetta edures more pain after being raped by Adebisi. Meanwhile, Alvarez is bumped out of the Latino power seat by Raoul Hernandez, a.k.a. El Cid. New inmate Jiggy Walker claims he was Gov. Devlin's personal crack dealer. The two go head-to-head in the media before Walker is discredited and sent to genpop. Reimondo finds out that Giles murdered the man who killed her husband and Dr. Nathan confronts O'Reily about her husband's death. Schillinger's plan to destroy Beecher approaches fruition when Beecher falls in love with Keller.

Cyril O'Reily, Ryan's brother comes to Oz and is immediately violated by Schillinger. Ryan tries to get him away from OZ, but Cyril instead lands in the hole. El Cid tells Alvarez the only way he can "stay in the game" is to "pluck out" the eyes of a prison guard, Rivera. Bellinger and Adebisi exchanging love letters without meeting. Nappa, the new Wiseguys leader, wants Adebisi to be punished for raping his godson Peter Schibetta. Robert Sippel, a Catholic priest who spent ten years in OZ for molesting a 14-year-old boy is released and but Poet returns.

When Cudney threatens to spill the truth about Cyril's "wins", Ryan solicits Kosygin for help. He then schemes to have Kosygin and Stanislofsky eliminated and finally, tips off the hacks to get Hernandez and Ricardo busted. Busmalis gets a welcome visitor. Sister Pete's questions keep rising after sessions with Keller. Nappa continues working on his new project. Beecher asks Said for lessons in the Islamic faith.

Mobay has his first meeting with Adebisi. Glynn fires McManus after Tim makes a foolish outburst during the slain CO's memorial service. Sister Pete still wrestles with ending her service as a nun. Beecher's dad pays a visit and gives an update. Schillinger is visited by his other son, Hank. Said's decision to help Cramer secure a new trial is met with strong opposition by the Muslims. Poet grieves and ponders his next move now that Wangler and Pierce are dead. O'Reily's plan to get the cell phone backfires and results in another inmate's death. Bellinger returns to Oz to await her impending execution.

McManus finds he is unable to turn his back on White. Beecher tells the parents of the young girl he killed that he's up for parole. Howell tries to blackmail O'Reily so she can get to Cyril, but he throws her for a loop--and then O'Reily is thrown himself by a family secret.

After recovering from his shank wound, Alvarez gains a follower. Busmalis starts a letter writing campaign to get "Miss Sally's Schoolhouse" back on the air. Rebadow finds a way to raise the money for his grandson's treatment. Jia Kenmin returns to Oz after recovering from the coma induced by a blow from Cyril. After Schillinger's released, Redding and Morales form a pact to eliminate the Italians from the drug trade. Schibetta makes a move on the Aryans only it backfires with terrifying results. Kirk continues planning ways to kill Cloutier. After carrying out messages he "received" from Cloutier, Hoyt confesses to all his past murders. Cloutier makes a move that mystifies everyone.

Three generations of Alvarezes—all prisoners at Oz—are united when the partiarch, Ricardo, is found face down in his cell, suffering from Alzheimer's disease. Meanwhile, Beecher, who as Schillinger's "prag" has been forced to wear women's clothes, flips out after taking PCP.

The hack ain't comin' back, and everyone's trying to figure out who did the deed; especially Schillinger and Said. McManus hires a new officer Sean Murphy who's also a friend of Tim's. Despite Glynn's reservations, an inmate boxing program is is created and inmates get psyched for the competition. While closely shaving Hill, Coyle gives the gruesome details of his crime, which include the death of an infant and the discovery of indisputable evidence to his claim. Disgusted, Hill decides Coyle should pay and gives the info to Warden Glynn. Adebisi gets approved to work in the AIDS ward. While Howell and Wittelsey converse about McManus, he appears with bad news for Wittelsey. Meanwhile, Schillinger's son Andy has been arrested and is due to arrive to Oz any day. Keller, stir-crazy from being in protective custody, goes back to Em City with painful results. Alvarez begins deteriorating now that his medication has been eliminated.

New inmate Burr Redding arrives and stands ready to assume control of the drug business. Dr. Nathan returns. Tidd approaches Schillinger with a plan to kill Said. Several Asian refugees are housed in Em City while the government decides their fate and they unwillingly get caught in a power struggle between Morales and Redding. Glynn hires an energetic new assistant who piques everyone's interest.