In the 'Emerald City' experimental unit of Oswald State Penitentiary, we meet some of the diverse inmates who exist in a pecking order of Gangbangers, Latinos, Muslims, Westies, Aryans and Wiseguys.

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 both from their wives and (in one case) family members who are also in prison.

Friction is growing in the wake of two deaths so Said, Wiseguy leader Schibetta and Gangbanger Jefferson Keane are brought together by Warden Glynn, who tells them to keep their boys quiet or else he'll lock the prison down.

Governor Devlin has reinstated capital punishment in the state--and the first Oz prisoner scheduled to die is Jefferson Keane, who killed a Latino in their skirmish. Before he's executed, Keane donates a kidney to his ailing sister.

The infiltration of drugs into Oz has reached scary levels, and the efforts of McManus and Glynn to find out who's smuggling backfire in a deadly way. Despite a lockdown, drugs continue to trickle in--and the blame shifts to corrupt officials.

Ricardo is discovered to suffer from Alzheimer's; Beecher flips out and sends Schillinger to the hospital; mob boss Schibetta develops stomach problems thanks to some ground glass; and Said has a heart attack.

A recovered Said ostracizes Huseni Mershah for turning his back on him when he was dying--and orders all the Muslims to cast him out. Impressed by Said's power, Groves decides to kill Glynn in his honor, but ends up stabbing an officer by mistake.

After a visit with his sons, Schillinger realizes he needs to get paroled. He convinces McManus to let him return to Em City with the condition that he leaves Beecher alone. Beecher comes out of the hole hell-bent on making sure Schillinger doesn't get paroled. McManus gets wind of Wittlesey and Ross' contraband operation and orders her to shut it down. Ross makes it very clear to her that this will not happen. The Muslims meet and discuss how the riot will begin. However, two rednecks beat them to it by fighting over a game of checkers. This causes all the inmates to get involved and they quickly overpower the COs who are trying to break it up. Said orders the Muslims to get out and seize control. Said pulls out the gun he acquired from a rookie CO and fires a shot into the air, causing Em City to quiet down. Said meets with Ross, Adebisi, O'Reily and Alvarez to discuss strategy and demands. Said agrees to let O'Reily, Ross and Adebisi control the main gate and Alvarez will control the hostages. Dobbins was seriously injured during the initial uprising and Hill convinces Vayhue to step up and help. Vayhue and Dobbins leave Em City only to be beaten up by SORT. The hostages require medical attention, so Alvarez and Said vote in favor of a doctor. However, Adedisi, Ross and O'Reily vote no. Governor Devlin orders the National Guard to surround the prison and take it back, but Glynn and McManus think they should see the demands first. McManus volunteers, to Devlin's disgust, to enter Em City to deliver food and check on the hostages. He tries to get COs Armstrong, Mineo and Wittlesey free in exchange for himself. He gets Armstrong and Mineo released, due to their injuries but Wittlesey has to stay. After reading the demands, Glynn realizes that the prisoners are being quite reasonable, however Devlin orders the National Guard and SORT to re-take Em City anyway. Meanwhile Ross' men and Adebisi's are constantly fighting, so Said tells O'Reily to switch Ross' men with Alvarez's at the front gate. A short tie later, Adebisi's men start to fiend due to the depletion of heroin, resulting in a major skirmish. Just as that situation is resolved and the Homeboys are tied up, the lights go out. Said realizes the situation and orders Ross to bring out the hostages as a front line of defense. Soon tear gas is thrown into Em City, then a tractor breaks through the barricade and gunfire rings out in Em City.

Season Two premiere. 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.

Ten months after the riot, Em City is reopened. A recovered McManus creates a council of group representatives to keep order, and initiates classes to help inmates get high-school equivalency diplomas.

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 Hill's judge is convicted of accepting bribes, Said takes up Hill's case.

Augustus Hill's appeal is denied, despite the efforts of Said, who has better luck with Poet's poems. Meanwhile, O'Reily survives his lumpectomy, and now focuses his attention on Dr. Nathan.

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.

Schillinger attempts to enlist Said to get him out of jail. Recovered from being poisoned, Schibetta is brutalized by Adebisi, losing 'control' of Oz. Meanwhile, Alvarez is bumped out of the Latino power seat by Raoul Hernandez, a.k.a. El Cid.

Cyril O'Reily, Ryan's brother, is imprisoned and falls under Schillinger's control. Ryan tries to get him away into Em City, but Cyril winds up in the hole. El Cid tells Alvarez there's only way he can 'stay in the game.'

In the Season Two finale, Wittlesey is transferred to general population and replaced by Karl Metzger, a Nazi. Mack and another Aryan try to escape through Busmalis and Rebadow's hole. Hill gets the idea of escaping Oz by hiding in a coffin.

Season Four premiere. The world of Oz--an experimental prison within a prison known as the Emerald City--reopens its doors with the inmates still on a 24-hour lockdown and prison officials struggling to end the hostilities.

The African-American inmates point the finger at McManus for letting Em City get out of hand. After that and his recent erratic behavior, McManus gets the ax from Glynn. Mobay's cover is almost blown.

Glynn learns from Adebisi that he was given the gun by former C.O. Hughes. Morales enlists Rebadow's help in taking Hernandez's place in the drug ring run by Adebisi and Pancamo. Mobay finds himself in a dangerous position.

Em City gets a new Unit Manager, Martin Querns, whose methods are hardly orthodox. Beecher's torment over his missing children is worsened when Schillinger presents him with an unexpected package. McManus returns to Oz in a new capacity.

As Querns implements his new course of action, the dynamics of Em City start to change, causing friction with Officer Murphy. Beecher falls deeper into depression as he wonders about the fate of his children.

In an effort to reduce violence, white inmates are transferred out of Em City. Said and Arif talk to Querns about the negative impact of his changes, but their efforts are in vain. Mobay gets in good with Adebisi's crew...but pays a price.

With things wild in Em City, O'Reily begins a surprising affair. Zabitz asks Schillinger for protection from Keller--who tries to get into the rehab program to make amends with Sister Pete. Beecher looks to get even with his children's kidnapper.

After Hughes' attack on Devlin, Glynn withdraws from the race. Miguel Alvarez is still on the loose. Supreme Allah receives an unwanted surprise. Hill pays big time when he tells Mobay he knows he's undercover. Meanwhile, Said does the unthinkable.

Six months have passed. Said was acquitted of Adebisi's murder on grounds of self-defense. "Up Your Ante," a game show, has joined Miss Sally in the prisoner's TV lineup. McManus and Glynn have done their best to keep the events leading up to Adebisi's death a secret. News producer Lisa Logan tours Oz in preparation for the arrival of hard-hitting reporter Jack Eldridge, who will also be spending a night with the new inmate the cameras will follow around on his first day. That man is Omar White, a jittery, homophobic addict fiending for drugs. Busmalis drives the cameras away. After an interview with Beecher Lisa considers focusing the piece on his struggles in Oz. Beecher taunts Keller and Ryan with on camera hints of their involvement in the murders; Keller threatens Ryan when Ryan wants to deal with Beecher; Pete dodges questions; Tidd interrupts a tense moment between Lisa and Vern. After a mention of Adebisi's drug-and-sex videotapes by Poet, Lisa decides to make the piece about the mystery surrounding his final days. Eldridge arrives, digging for information on Ryan after Ryan hints at their past connection. Eldridge blindsides Said with questions about his part in Adebisi's death. Worried about damage to Em City and his and Glynn's careers, Tim points Lisa toward the man he blames: Querns, who kept quiet in exchange for Glynn keeping quiet over his unethical methods. Per Glynn's advice, Querns turns down requests for an interview; per Querns' advice, Glynn destroys the tapes. Glynn and Jack have an off-the-record conversation, leading Eldridge to realize Glynn was a good man caught up in a situation he couldn't control. Jack cancels the Adebisi story. Offering him a constant supply of drugs, Ryan manipulates White into helping him settle an old score against Eldridge. Unfortunately, White tries to attack Eldridge directly in front of the guards. White goes to solitary. Eldridge chooses Cyril for his podmate, sensing good story potential. Cyril, who hasn't been taking his medication, remembers Eldridge and blames him for his mother getting cancer (Eldridge did a piece on Ryan on Cyril when they were in charge of their local Irish gang, painting them as monsters. Their mother developed and died from cancer not long afterward.). Cyril beats Eldridge to a pulp. As he recovers from serious injuries, the network decides to cancel the piece on Oz. Lisa resigns in protest.

New inmate Burr Reading arrives, ready to take charge of the African-American drug scene. Dr. Nathan returns to Em City, and finds the biggest adjustment is dealing with her feelings for O'Reily. Tidd tries to strike up a deal with Schillinger.

Morales looks to pit the Chinese against Redding. Alvarez offers Glynn his services as an informant as a way out of solitary. Dr. Nathan announces that Em City inmates will be selected to test a trial drug that could reduce their time behind bars.

O'Reily regrets getting Cyril involved with the trial drug when it starts taking effect. Meanwhile, Giles' request for an unusual execution creates controversy and the Chinese refugees are deported...but not before plotting revenge on Morales.

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.

McManus calls a superficial truce between Redding and Morales. Basil finally sees his wife, but Hughes ends up spoiling their happiness. Meanwhile, Cyril's latest outburst proves to be the last straw.

McManus can't turn his back on White. Beecher tells the parents of the 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 secret.

In the Season Four finale, Hill discovers where his true allegiances lie in Oz. Redding's plot to use the Colonel against Morales has an unexpected outcome. Beecher's agony about his parole hearing leads to a shocking season climax.

In its fifth season premiere, Oz re-opens in the wake of major renovations that had to be completed following a gas explosion.

McManus thinks White may reform if he spends quality time with Said; Alvarez offers Guerra a unique solution to their dispute; O'Reily's mother, Suzanne Fitzgerald, begins a community service term teaching music at Oz.

Brass wants to know who cut his tendon; Redding and Morales form another uneasy alliance; Rev. Cloutier's mysterious influence over his followers grows more intriguing; and Keller returns to Oz, only to be hit with an ID from an old murder charge.

Penders, Hill and Alvarez are given a chance to train seeing-eye dogs; Martinez gives Brass a 'cocktail' he definitely didn't order; the love triangle between Beecher, McClain and Keller becomes more complicated.

Robson stirs up problems between White and Said. Meanwhile, Pancamo's illness might save some work for his enemies, Schillinger makes a friendly but suspicious overture towards Beecher, and Morales seeks revenge on his sister's abusive husband.

As Cyril's trial gets off to an inauspiciously cold start, tensions between Mukada and Kirk come to a boil. Also, a priest named Meehan lands in Oz while White and Said turn over a new leaf in their relationship.

Hill's recovery leads to renewed friction between Redding and Morales, Alvarez gets his wish as the 'Man's Best Friend' program is finished and Meehan presents some revolutionary ideas to help Cyril.

In the Season Five finale, Robson goes to extremes to remedy his gum dilemma, Meanwhile, McManus struggles with personal turmoil over his decision to stay at Oz and Rebadow deals with his grandson's fate.