Having a lifelong fascination with tunnels and caves, Cave Carson became an expert on the world within the world, and gathered a highly skilled team to help him in his explporations. This team included ex-convict, strongman and tunnel expert Bulldozer Smith; renowned geologist Christie Madison; and devil may care adventurer and fellow spelunker Johnny Blake.

Accompanied by Bulldozer's pet lemur, Lena, these four devoted their lives to uncovering the hidden secrets of the world beneath the earth. With the aid of the Mighty Mole - a remarkable digging machine invented by Cave and constructed with funds he had received as a result of his underground discoveries - Carson and his comrades uncovered the remains of ancient cities, located lost civilizations now living underground, and battled evolutionary throwbacks and even various alien life forms, all dwelling inside Earth.

More recently, Carson was banned from further exploring when he accidentally discovered an ancient object the government had classified top secret. Joining a number of other once famous adventurers whose careers were in decline, these "Forgotten Heroes" uncovered the secret of this mysterious object and helped to save the world.

By this time Carson had lost touch with his three colleagues and he remained part of the "Forgotten Heroes" team.