In one of Maricopa's primary men's facilities, the Fourth Avenue Jail, when inmates are not in their small, two-person cells, they can work out in an indoor rec room, or in the common area between their cells. But every afternoon, many of the inmates shift focus from their bodies to their bank accounts. Since inmates are not allowed access to cash, they have another way to pay gambling debts. The losers must purchase snacks or other items from the jail canteen for the winners. They pay for canteen through debit accounts that friends or relatives on the outside deposit money into. But a losing hand can bring serious consequences.

While visiting Limon Correctional, the Lockup crew is greeted by angry inmates and the cell extraction team is called in to help.

Idle time leads to mischief in prison.

Intimacy in prison.

Life inside prisons throughout Scotland and Belgium.

Inmates' unwritten rules known as the Convict Code.

Behind the walls of six maximum-security prison in Serbia, Poland, and the Czech Republic.

Inmate violence including riots, shanks and attacks on officers.

Grantt Culliver controls the disruptive inmates of Holman Correctional Facility.

Inside the maximum security facility in Eastern Iowa.

An inmate behaves erratically; an accused murderer faces the death penalty while his girlfriend is being held in the women's wing; a new female inmate raises havoc; a raid catches an inmate by surprise.

A look at life in jail, which generally houses inmates who are waiting for their trials or serving relatively short sentences.

Violence at the Limon Correctional Facility in Colorado.

On a regular basis camera crew explore where even the most heinous violations are an every day activity.

An inmate's actions lead to an emergency response; a repeat offender accused of assaulting her mother relies on her daughter for support; an inmate focuses on his brain; another inmate is accused of an unthinkable act.

Dangerous inmates are segregated from the rest of the prison population.

Relationships both inside and outside the prison walls.

The prison's annual poetry slam.

The daily grind of prison life has been known to push some inmates to the brink.

Inmates at San Quentin State Prison find ways to fight boredom.

Cases involving a suicide, a stabbing and a man found in a Beverly Hills fountain are investigated by the Los Angeles coroner in the Season 8 premiere.

Correctional officers search prisoners for weapons.

See how the once-infamous Rikers Island jail has reinvented itself.

Oklahoma inmates tell their own remarkable stories.

Half of Chicago's Stateville Correctional Center's inmates are imprisoned for murder.

LA County Jail is a system that is overcrowded, tough on gangs, and struggling with an increase in racial violence.

Inside the maximum security prison inmates call 'the end of the world.'

A profile of San Quentin State Prison in California; one of the most famous, most notorious penitentiaries in the world.

Behind the walls of Kentucky's only maximum security prison.

California's Kern Valley State Prison opens its doors in 2005.

Revealing of how these women deal with relationships and struggles.

A female housing unit inmates call a party house will turn a new inmates life upside down.

One of the most violent and volatile penitentiaries in the nation.

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. And like all inmates at Maricopa, some are awaiting trial while others have been convicted and are appealing their verdicts or sentences. They are isolated in very stark cells 23 hours a day and get one hour of rec time in an empty concrete room with a skylight located right next door to their cells. Without the distraction of television, radio or a cellmate, even the most hardened criminals can break under the pressure. One gang member makes a desperate cry for help by putting a noose around his neck, then says, "I just need somebody to talk to." And on the other side of the jail, completely isolated from other inmates, Maricopa's four most dangerous women form a notorious sisterhood

Meet Danny Pritchett, who has a history of being a predatory inmate, both inside and outside of prison. He was transferred to Santa Rosa after proving to be too much to handle at other Florida state prisons.

A dangerous combination of gangs, drugs and boredom encourages inmates to commit violent offenses in prison.

Miami's prison system.

Some prisoners resort to violence while others become victims.

Many inmates use their time in jail to get clean off drugs and get their lives on the right path. Others, however, simply can’t wait return to the dangerous lifestyle of the streets.

A 20-year-old inmate speaks about how he grew up on the streets and what motivates him to turn his life around.

The most extreme Lockup stories ever. These are the prison stories best described by one word. And the word is... HARDCORE.

Over the past ten years, the structure of local gangs has changed and that's had a serious impact on the Suffolk County jail. In this hour: an inmate takes his fights from the street to the halls of the jail, and his boyhood friend follows his example; two brothers turn to crime to support their habits, and now one faces the prospect of hitting the streets again.

Boston, Massachusetts is by any standard a world-class city. But ever since its colonial days, some have called it a fighting town. And located in the heart of the city is a place for anyone who does their fighting outside a ring. More than 12,000 people a year pass through the doors of Boston's Suffolk County Jail. And with an average daily population of 2,700 male and female inmates, someone reaches their boiling point virtually every day of the week. For those inmates all too willing to throw a punch... the jail has a special place: The Box. As one inmate says, "Separated from everything so you learn to deal with it. It's called 'The Box Life'."

While Boston, Massachusetts maintains its colonial past, it's ranked as one of the world's leading metropolitan areas for education and innovation. In the heart of downtown, however, is a reminder that not everyone is on the right track. In this hour: an old school bank robber maintains his swagger; an inmate with an imaginary friend proves to be a challenge for the jail, and a shocking act lands his sister behind bars, as well.

Nine of the most violent criminals from the 'Lockup' series give chilling accounts of their crimes.

The Corcoran State Prison, located in an isolated valley, is one of California's largest maximum-security institutions.