The podcast episodes discuss the legends and evidence surrounding various underground structures and complexes around the world, which challenge mainstream archaeological understanding of human history.

These include the alleged underground city in the Grand Canyon, the subterranean world of Agartha, the Hypogeum and other megalithic structures in Malta, and other examples that suggest the existence of lost advanced civilizations.

The episodes explore how these underground sites may contain artifacts, architectural features, and other clues that point to the possibility of prehistoric cataclysms and the transfer of knowledge from survivors to primitive humans after a great flood or other catastrophic event.