Forbidden Worlds #40 (1956)

Sergeant Arthur Jenkins, haunted by a wartime mission where he ditched a fortune in gold to survive a swim, spends years searching the Mediterranean coast for the lost treasure. Years later, on his honeymoon with his new wife, he and his wife discover something strange while diving—possibly the very belt of gold he once lost.

When landscape painter Harry Lazarus moves to the western plains, he’s drawn to the beauty of the land—until a mysterious phone call from a hollow voice repeatedly directs him to dig between two great pines at Whitefaced Bluff. Though he dismisses the strange instructions as a prank, the discovery of a buried treasure hoard sets him on a path that challenges his beliefs about fate, ancestry, and the past.

Frank Embree stumbles upon a hidden underground civilization beneath Arizona, drawn in by a failed uranium prospecting trip, only to find himself in a vast, gold-rich society that has lived in secret for a million years. As he adapts to their peaceful way of life, he becomes obsessed with a massive ruby idol in their sacred temple, setting in motion a plan to steal it—though he must first navigate their strict, nonviolent culture and find a way to exploit their secrets.