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.
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.