Episode 4

Ancient Aliens explores the controversial theory that extraterrestrials have visited Earth for millions of years. From the age of the dinosaurs to ancient Egypt, from early cave drawings to continued mass sightings in the US, each episode in this hit History series gives historic depth to the questions, speculations, provocative controversies, first-hand accounts and grounded theories surrounding this age old debate. Did intelligent beings from outer space visit Earth thousands of years ago?

Joe Lycett takes a ruthlessly efficient approach to travel, covering everything top tourist destinations have to offer in just 48 hours.

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.