What is the thesis and ultimate purpose of the book Newjack?

Ted Conover wrote this nonfictional book about Sing Sing, a notorious prison in New York. His purpose was to provide an eyewitness account of life inside the penal system. A "newjack" is a rookie prison guard. Conover became a newjack so he could explore the culture behind bars. After his year-long experience in Sing Sing, the purpose of the book ultimately became to shed light on the necessity of reforms in the prison system.
One of the major themes in the book is the role of masculinity and aggression in prison relationships. There are many characters in the book who display a level of masculine aggression that reaches dangerous, destructive levels. Conover often finds himself reacting in more violent ways than he anticipates as he acclimates to an environment that is steeped in male aggression and abuse. He ultimately discovers that the prison environment has a dehumanizing effect on prisoners and prison guards alike. He sees prison officers become "violent once enmeshed in the system." He concludes that a conflict exists between the need to isolate criminals from society and the need to reform a system that treats criminals more like animals.