>> pelican bay is the toughest prison in the california prison system. it's where the worst of the worst go to. the first time we sent a "lockup" crew was weeks after they suffered their worst gang riot in history. and there was still tension in the air as the crew walked in through those gates. >> the riot fought primarily between black and hispanic inmates lasted a little over 30 minutes. one inmate was killed and dozens of others were stabbed or beaten. when we returned five years later, the tension was still palpable. >> one of the interesting things about pelican bay is there really seemed to be two systems of rules, the prison administration and then the rules of the gangs. and there's this constant tension between the two. it's like a modern day sparta. they have trained themselves mentally, physically for a wartime situation. and it feels like a war. it feels like a wartime prison, pelican bay. >> correctional staff told us