this building. >> but for inmates in the shu, the monotony brings a horror of its own. they told us what it was like to spend 23 hours a day in a windowless concrete cell, sometimes for years at a time. >> it's like you're always trying to find a way to come up for air. this place suffocates you. you know what i'm saying? >> it's a tomb for me. you know? it's like a tomb. it's like a tomb, a concrete tomb. what if they would have sent these punk ass dudes to -- and he would have succeeded in killing them, right? >> during our first day on the shu, we walked into a heated exchange about murder. >> what you saying about the killer? you saying both killer. >> but it wasn't about prison violence. >> showed up, saying that macbeth sent him. >> it was about shakespeare.