A team of Americans attempts to solve one of the great mysteries of World War II. With the help of an eyewitness, they explore a mountain in the Philippines where Japanese general Yamashita is believed to have buried a vast treasure during the war.

Digging continues at Breach-6, but when the team unearths a possible water trap, excavation is put on hold. To find another way into the mountain, the team conducts a LiDAR scan that reveals a cave, perhaps used by Japanese soldiers during the war.

After discovering a bomb marker, the team brings in an explosives expert to search a cave that may have been a headquarters of General Yamashita during the war. Inside, they uncover a potential booby trap, along with their first hint of treasure.

The team triggers a possible water trap in the cave and is forced to stop digging. Martin Flagg believes the Story Rock indicates a tunnel behind a waterfall and the team brings in a Navy diver to explore the plunge pools and search for an entrance.

Unable to find a tunnel at the waterfall, the team is guided by an animal marker to a boulder carved in the shape of a turtle, which leads them to a golden lily symbol indicating a secret backdoor entrance.

The team attempts to prove if a tunnel exists behind a unique formation of rocks they believe is a secret backdoor entrance into the mountain. Battling a typhoon and possible Nazi concrete, the team ultimately finds proof of a void 40-feet below.