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.

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.

The unexpected arrival of Mayor Loewen at Oz spurs an ironic turn involving Schillinger and Beecher. Meanwhile, Dr. Nathan discovers why solitary inmates are getting sick. A new business plan within Oz inspires Redding.

Tobias learns who killed his father before being released from prison. Cyril begins shock therapy while receiving an execution date. Said is allowed to start his own company.

Glynn receives mixed news on the toxic-poisoning problem. Meanwhile, Rebadow's relationship with the new librarian Stella hits a snag, Keller and Beecher work out an agreement, and Robson finally gets some redemption.

Arif and the others have trouble getting Augustus' book published. Tobias confesses to Chris he's started dating someone on the outside.

New inmate Idzik faces his enemies and requests a transfer. Meanwhile, the Loewen case grows increasingly complicated, the Muslims run into business trouble, and the inmate population comes together to support the O'Reilys.

Three new inmates arrive at Oz, one of whom is particularly close to the O'Reily clan. Meanwhile, the Keller-Beecher-Schillinger triangle gets even more pointed, and an awards banquet ends in a fateful discovery.

Querns is appointed the new warden of Oz. Brass attempts to get famous for a day. Tim tries to change the mindset of Said's murderer. Cyril is finally executed. Keller brings Tobias back to Oz for good.