Episode 6

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.

Literature professor Harriet "Harry" Wild is adjusting to retirement when she's mugged. While recovering at the home of her son, a detective in the Dublin police, Harry gleans a clue for his current case. But when she's rebuffed, Harry decides to solve the crime herself. Recruiting an unlikely young sidekick, she finds a new path as a private investigator.

Tracker features lone-wolf survivalist Colter Shaw, who roams the country as a "reward seeker," using his expert tracking skills to help private citizens and law enforcement to solve all manner of mysteries while contending with his own fractured family.

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.

Across continents and decades, five brilliant friends make earth-shattering discoveries as the laws of science unravel and an existential threat emerges.