Season 4

Chad and Eric explore a deep cavern while Duane discovers smoke vents.

Duane recruits treasure hunter Josh Feldman, who recommends a new plan of action to find the Aztec gold. But before they can break ground, a local Timpanogos tribal elder visits the ranch with disturbing words of warning.

Eric and Chad encounter disaster while attempting to breach the void in the South Cave. A mysterious rumbling shakes the ranch, and James finds evidence of the Aztecs at the Bead Site.

Chad and Eric discover an abandoned mine deep in the mountains and suspect they are being stalked. At the Bead Site, the team unearths evidence of sacrifice.

Chad and Eric find signs of gold at the abandoned mine, but nightfall brings an unwanted stalker to their camp. At the Bead Site, the team unearths an ancient structure.

Disaster strikes when Duane and Charlie attempt to drill down a smoke vent at the Bead Site. Chad and Josh follow the fault line back to the collapsed mine. Eric explores an indigenous site in Ohio that holds clues to Blind Frog Ranch.

Believing they might have drilled into an Aztec aqueduct at the Bead Site, Duane and James head to Mexico to meet an expert. Chad and Josh trace the underground waterway to a remote lake that might be protecting a secret.

A hidden cave entrance below a lake could finally lead the team into the Keyhole Chamber. After training in Florida with some of the best cave divers in the world, Chad navigates a deadly maze of flooded tunnels and makes a shocking discovery.