Lockdown plunges head-first into the gritty underworld of some of America's most fearsome prisons. Three thrilling hours provide an unprecedented immersion into life in the "big house": vicious gang leaders, a "prison pretty" newbie, and a gangster turned rat. In this world of absolutes, predators stalk their next prey, gang commanders order hits from isolation, and inmates are armed with deadly weapons. But the prisons are striking back. Institutional weapons of choice…