Inside Maximum Security

S1 E3: National Geographic goes inside one of the America's most secure prisons - Oak Park Heights Supermax. This state-of-the-art fortress houses criminals other prisons can't handle. Built partially underground, the Supermax combines innovative architecture, cutting-edge technology and an expertly-trained staff to control some of the most violent prisoners in the system. But the system's most dangerous inmates are always looking for ways to fight back, and their criminal ingenuity puts the Supermax to the test.