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.

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.

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.

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.

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.

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.

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.

Ryan and Howell get frisky. After leaving the hole and apologizing to Busmalis for the stabbing Rebadow suffers an attack due to a brain tumor. Busmalis reacts by doing what he does best--start another tunnel. Unbeknownst to the doctors and everyone else, Cyril's recovering psychologically more than he can actually show. Arif confesses to Said about his own demons and asks for forgiveness and help. Said plots with McManus to end Querns' and Adebisi's control. Hank Schillinger beats the kidnapping rap and once Beecher finds out, he plots with Pancamo for revenge. After Keller reveals his plot to kill him, Eli Zabitz asks Schillinger for protection. Schillinger agrees but sends Robson to eliminate Zabitz instead. Hughes, now raging beyond sensibility, makes an attempt on Devlin's life at a press conference. Keller and Father Ray have an intense discussion about Beecher.

O'Reily is in for a surprise when a visitor reveals the truth about his past, while Cyril faces trouble for his difficult behavior. Meanwhile, Morales and Redding lay out plans that could lead to all-out war in Em City.