Episode 4

An emotional thrill ride through the day-to-day chaos of the city's newest state-of-the-art trauma center and into the lives of the courageous doctors, nurses and staff who hold it all together. This is one of those days.

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.

Real-life mysteries. Investigative reporting. Justice. Dateline is the long-running, award winning newsmagazine bringing viewers stories ranging from compelling mysteries to powerful documentaries and in-depth investigations. Hosted by NBC News' Craig Melvin, each episode of Dateline: Secrets Uncovered incorporates the classic elements of drama and great storytelling: good guys, bad guys, conflict with the highest stakes, suspense and resolution. Hear the chilling tales directly from those most affected and involved, including investigators tasked with cracking the case and the families confronting tragedy. In every story we tell, we help the real people who lived the events share their journeys with you.

9-1-1 is a fast-paced exploration into the lives and careers of first responders – cops, paramedics, firefighters – the people who put their lives on the line to save others.