The first time I caught this show was by accident but I was hooked after about two minutes. Many of the actors will be recognisable from shows such as Lost, Law and Order, The Wire, Rescue Me and The Sopranos. This show has some of the best writing and characterisation that has ever been on television and definately holds up ten years later.
Oz is the nickname for the Oswald State Correctional Facility, but the majority of the plot arcs are set in Emerald City ("Em City"), an experimental unit of the prison, where the unit manager tries to emphasize rehabilitation during imprisonment.
Life in Oz is tough and the show revolves around the plotting and schemining of the inmates and as a result daily life in Em city often includes murder, violence, drug use, rape, homosexuality and religious and ethnic tensions.
Oz does not try to speculate on the cause of criminal behavior by the inmates, indeed the show takes place exclusively behind the prison walls except for when a particular inmate is introduced by showing the crime which he is in prison for. This helps to vrete a very claustrophobic and tense atmosphere. One of the perspectives shown by Oz is that the rehabilitation of the prisoners is impossible when the system is largely corrupt.
The true masterstroke of Oz is that it refuses to pigeon hole its characters. Even the most sociopathic prisoners are shown to have moments of humanity while some of the nicest prisoners commit very bad acts. It is also notable that some of the most 'normal' prisoners are in prison for crimes that are far worse than some of the worst prisoners and as a result you as the viewer end up feeling sympathy for some of the characters before remembering that they have killed a child or a cop.
I had given up on this show ever being released region 2 so I have imported every season but I would strongly recommend this show to anyone who like good, gritty drama.