Episode 4

District 21 of the Chicago Police Department is made up of two distinctly different groups. There are the uniformed cops who patrol the beat and go head to head with the city's street crimes. And there's the Intelligence Unit, the team that combats the city's major offenses - organized crime, drug trafficking, high profile murders and beyond. These are their stories.

No job is more stressful, dangerous or exhilarating than those of the Firefighters, Rescue Squad and Paramedics of Chicago Firehouse 51. These are the courageous men and women who forge headfirst into danger when everyone else is running the other way and whose actions make the difference between life and death. These are their stories.

In a ruined and toxic future, thousands live in a giant silo deep underground. After its sheriff breaks a cardinal rule and residents die mysteriously, engineer Juliette starts to uncover shocking secrets and the truth about the silo.

It's Always Sunny in Philadelphia is an American comedy series about four friends in their late 20s with clear sociopathic tendencies who run an unsuccessful Irish bar, "Paddy's Pub," in South Philadelphia. The series deals with a variety of controversial topics, including abortion, gun control, physical disabilities, racism, sexism, religion, the Israeli/Palestinian situation, terrorism, transsexuality, slavery, incest, sexual harassment in education, the homeless, statutory rape, drug addiction, pedophilia, child abuse, mental illness, gay rights and dumpster babies.

In the criminal justice system, sexually-based offenses are considered especially heinous. In New York City, the dedicated detectives who investigate these vicious felonies are members of an elite squad known as the Special Victims Unit. These are their stories.