In the Season Six premiere, Alvarez and Schillinger are let out of solitary and placed back in general population. Meanwhile, a mourning Rebadow's spirits get a lift when he is transferred to the library and meets the new librarian, Stella Coffo.
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.
Schillinger has a disappointing visit with Mayor Loewen. Glynn has to face the truth about the toxic-poisoning problem in Oz. Down in solitary, Officer Brass spends some quality time with Morales. Meanwhile, Cyril O'Reily undergoes unusual therapy.
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.
Everyone in Em City has a different opinion of the newest inmate, Idzik. Meanwhile, Alvarez receives some shocking news, Murphy makes a confession to Glynn, and Beecher finds himself in a perilous position as a result of his devotion to Keller.
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.
In the series finale, Oz is in upheaval after the return of Martin Querns. Meanwhile, Howell and Robson each receive troubling news and the O'Reilys try to make amends. Finally, the prison production of 'Macbeth' ends with a staggering final act.