In a Bolivian jungle, Adam and Caveman Rob pursue the fabled Executioner Wasp, Warrior Wasp, and Goliath Bird-Eating Tarantula. One causes a medical emergency, and another delivers a nightmarish bite that leaves Adam's arm partially paralyzed.

Adam and Caveman Rob head to South Africa to face the giant Bark Scorpion, the tiny Uroplectes Scorpion, and the highly venomous Lion Fish. Big pain comes in small packages, and the effects of marine animals' toxins are truly the next level of pain.

In Mexico, Adam and Caveman Rob tango with 2 torturous animals-including one that topped Justin Schmidt's pain scale. The guys up the stakes by covering their hands with hundreds of Harvester ants and 2 Pain Index records are shattered.

In Africa, Adam and Caveman Rob search for the Nile Monitor Lizard and the Velvet Ant but are attacked by an even deadlier animal and are lucky to escape with their lives. The guys experience a brutal bite that makes them question their mission.

A dangerous underwater hunt for the potentially deadly Scorpion Fish in the Baja California ocean leads to a toxic sting that puts Adam in danger and matches the highest pain score to date, while the Toe biter results in the weirdest pain profile yet.

Adam and Caveman Rob journey to the Asian island of Bali and face off with the Fire Urchin that almost knocks out Caveman Rob, and the Rove Beetle, which surpasses the record for the highest pain score to date and causes permanent damage.