O’Reilly cuts a Machiavellian figure as he weaves between the show’s many cliques and tribes, whispering of betrayal here, pointing the finger there, moving his enemies around like chess pieces and dispatching them with the sure-footed guile of a psy-ops agent.

But even a man as lost to civil society as Ryan O’Reilly is at least explainable, even if he isn’t wholly redeemable. We meet his family, and in them we see reflections of O’Reilly’s past and potential: we see his contempt for his selfish sack of shit father whose actions – and indeed lack of them – doubtless contributed to his journey down his one-way, wayward path; we see the feelings of love, duty, anger, irritation and guilt he feels towards his disabled brother, Cyril (Scott William Winters, Dean Winter’s real-life brother), with whom he shares a cell; and we see how this relationship brings out both the best and the worst in O’Reilly.

Cyril entered adulthood just as much of a cold-hearted killer as his brother, but an accident left him with irreparable brain-damage and the IQ and outlook of a child. It’s the latter Cyril we first meet in Oz. Cyril is at once O’Reilly’s hope, humanity, and Achilles’ heel, and through him the show is able to examine how the penal system treats prisoners with special needs (Spoiler alert: not very well), while also exploring notions of memory, identity, blame, redemption, culpability and, of course injustice.

One man in Oz who could write a book about injustice (and at one point actually does) is the Muslim Brotherhood firebrand, Karim Said (Eamonn Walker). Karim finds himself in Oz thanks to his particular brand of fight-the-power political extremism, and once there never stops fighting: against the system, against sin, against prejudice, and, most notably, against his own demons, some of which are too powerful even for God to quell. Karim’s a man of deeply felt and held principles, in many ways a religious counterpart to McManus, both men sharing a predilection for righteous anger and a susceptibility to the sin of pride.

It’s hard to know whether Karim is brave or stubborn, fearless or feverish, self-sacrificing or arrogant, but he’s undoubtedly one of the most fascinatingly flawed and complex characters on the show. If you’ve any scintilla of soul at all you’ll hopefully find yourself vicariously revelling in his many triumphs, perhaps even punching the air with glee. The final chapter of Karim’s story in Oz – sad, tragic and sudden – is either proof of the unknowable nature of Allah’s ultimate plan, or a victory for the forces of chaos in a cold and Godless universe. That’s for you to decide.