Legend has it that five hundred 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 the Cave Rover; the Villescas family makes a new discovery that could be an important clue from an old treasure hunter.

The hunt begins to heat up when the Miners in Nevada use a smoke gun to find another entrance to this dangerous tunnel system. In New Mexico, the Villescas family has to use some crossbow ingenuity to find their way into a sketchy mine.

The Dillman family seeks answers in the mysterious Weeping Cave; in Nevada, the miners bring an expert to look at a very unusual discovery from the mine.

The Villescas family talk with an expert about whether a spur they found could tie to the Conquistadors. The Dillmans use drones to locate an important ancient symbol, which could be a map. To find out, they must repel down the side of the canyon. And in Nevada, the Miners' search is sidetracked after a potential grave site brings up questions about who else was in their mine before them.