Actor Frank Grillo visits Mexico City, where he meets Julio César Chávez, speaks with aspiring boxers and learns the one rule of Mexican boxing.

In Thailand, Grillo sees firsthand why muay thai is known as "the art of eight limbs." Later, he visits a true titan of the sport.

Fighters from around the world travel to Myanmar for the World Lethwei Championship. Also, Grillo trains with an elite fighter.

In Israel, Grillo receives a lesson on Krav Maga, a unique style of hand-to-hand combat used by citizens and military forces alike.