It's a female housing unit with a reputation, one that inmates call "a party" and a "big sorority house" with a twist.

Located on the top floor of Maricopa County's Fourth Avenue Jail Facility, are the highest-security male housing units. These inmates have either committed violent acts in the jail or have been identified as gang members. Here, even the most hardened criminals can break under the pressure.

Lockup's crews are there when protesters gather against Maricopa County Jail's outspoken sheriff. How will he respond to critics of O Yard, where 80 percent of the inmates are undocumented immigrants?

The men of the Fourth Avenue Jail must come up with inventive ways to pay gambling debts. But a losing hand can bring serious consequences.

No matter the circumstances that brought them there, Maricopa County Jail in Phoenix, Arizona, will have a profound effect on who the inmates will become. And for some, their time in jail will reveal their true nature.

It's a world where tensions run high. And for a mother and son accused of a heinous murder, the daily drama can be overwhelming.

"Lockup" producers take the time to get to know dozens of inmates, following the action and watching the story unfold in front of their eyes. This is the story behind those stories.

The ex-leader of a white supremacist gang discovers the price for coming clean.

Lucky inmates find ways to cope with the past. Others are haunted by it. But for some, the past can return with a vengeance.

For most inmates, life boils down to three words. The first is respect. The second, reputation. The third, revenge.

If personal relationships can get complicated on the outside, they can be even more complicated behind bars.

In prison, time can be an inmate's worst enemy. Some find constructive -- if not unusual -- ways to fill it. Others depend on humor to pass it. And then there are those who can only hopelessly watch it tick away.

Arizona's Maricopa County Jail prides itself as, "America's Toughest Jail." But we went behind the headlines to find stories that ranged from the unexpected... to horrifying. And at the center of this most unusual jail, is one of America's most controversial figures... Sheriff Joe Arpaio.

Prison might be hell...but for some, it's especially so. On the mainline, they don't like cops, or the first time offender. And it can even be worse for the sex offender.