Legend has it that 500 years ago, a vast fortune in gold was hidden by the Aztecs somewhere in the American southwest; now, three families are closing in on what they believe is the location of the treasure.

The Dillman family completes the underwater dye test at Shadow Cave; in Nevada, the miners bring in a Cave ROV; the Villescas family makes a new discovery that could be an important clue from an old treasure hunter.

The Dillman family breaks out the excavator to dig up the mysterious marsh, which may have previously revealed an ancient artifact.

The Dillman family seeks answers in the mysterious Weeping Cave; the Villescas family builds a shaker box to help sift through material at a faster pace; in Nevada, the miners bring an expert to look at a very unusual discovery from the mine.

The Villescas family talks with an expert about whether or not a spur is related to the Conquistadors; the Dillmans use drones to locate an important ancient symbol that could be a map.

In New Mexico, the Villescas family decides to bring in more heavy machinery and a full crew to find conquistador gold; in Nevada, the miners' years of Aztec research is threatened.