Dude went away to prison for holding up a post office with a shotgun. Didn't kill anybody but was sentenced to 7 years off the bat. Ended up being such a nut in prison and wanted to become famous so he started fighting guards constantly and dong the most outrageous shit ever. Guy has been in solitary confinement for like 30 years and actually enjoys it.
The movie is more of a low-budget type of production that you would see at a festival but it really is awesome and it explores the mind of such an insane inmate/person. At first I thought it was super weird when I started watching it, but then I just let myself sink into the dark and crazy world that the movie is intended to portray. Not to mention Tom Hardy is an absolute badass and plays these types of roles so well. He's also naked and covered in blood while brawling with guards a lot throughout the movie which I found pretty funny and ridiculous.