Visiting with the youngest fire department in the United States, Todd Sampson is on a mission to uncover what the extreme life of an emergency responder does to the mind and body.

This week, Todd visits the Mongolian Kazakhs and examines how their bodies have adapted to the brutal conditions of Mongolia and how their existence depends on their alliance with animals.

Todd Sampson spends time high up in the Wudang Mountains of China at a school that teaches the ancient art of Kung Fu.

Trekking deep into the Amazon, Todd lives with a remote tribe, the Matses who still use traditional hunting techniques. Todd is ask to take part in a popular ritual, but soon find himself in trouble.

Todd Sampson heads to Iraq, joining an Iraqi shock troop in the Islamic State strong hold of Mosul. Overcoming his own fear, Todd heads out on a mission to clear buildings of the enemy and explosives.

Todd Sampson travels to India to live with holy men called sadhus, to uncover the reasons why they worship pain and endurance as part of their religion.