American treasure hunter John Casey returns to the Philippines with a new team and new technology, in a continued effort to solve one of the greatest mysteries of World War II. It's all hands on deck, when an advanced satellite scan of the mountain reveals massive metal deposits underground. Based on these results, the team targets three sites believed to be the access points to Yamashita's gold: a waterfall, a crater known as "Breach 6," and a camouflaged tunnel they uncovered last year.

With new evidence suggesting the location of a possible treasure vault beneath the waterfall, John is determined to find a way in; but mother nature is wreaking havoc on his plans. Meanwhile, surprising information is revealed about the knife discovered in the tunnel pointing to who could have left it behind. And finally, a promising clue uncovered at Breach 6 has the team going all in.

Exploration of the tunnel is put on hold after an explosive find. Meanwhile, another promising clue at Breach 6 leads Rick to believe they're on the right track. Finally, while John hits a roadblock on his search for a tunnel entrance near the waterfall, Bingo makes an incredible discovery that could lead him to Golden Lily treasure maps.

Left with no other option, John plans to drill across the mountain to get underneath the waterfall, but the weather won't make this an easy task. Meanwhile, Rick finds an artifact at Breach 6 that could confirm Japanese military presence on the mountain during World War II. Then, Levi and Geo make a grim discovery in the tunnel that risks shutting down the site indefinitely. And finally, Bingo meets someone with rare and valuable knowledge on the whereabouts of Yamashita's gold.

While John and Rick work to decipher a Golden Lily map, Breach 6 reveals its first piece of treasure. Meanwhile, Levi and Geo come up with a creative solution to get past a mysterious collapse in the tunnel. And finally, while drilling towards a possible treasure vault, John and Rob make a startling discovery, and come face to face with unexpected visitors.

As the team finally gets to the bottom of Breach 6, startling new evidence suggests they might be too late. Meanwhile, the miners trigger a hazard in the tunnel that threatens their safety. Finally, Bingo unearths alarming evidence a little too close to home, about who else could be after the gold.

When a dead end in the tunnel threatens to close the door on exploration, a back door opens. Using their recently decoded Golden Lily map, the team discovers new access points, hoping to get under the waterfall by any means necessary.

In the season finale, the team finally reaches the void space under the waterfall, giving them a glimpse of what lies inside. But excitement is short lived when unexpected visitors get in the way. Meanwhile, the team investigates leads for other possible Yamashita treasure sites throughout the Philippines, uncovering evidence that any one of their 25 new treasure maps could lead them to the Lost Gold of WWII.