Queen Medusa

From CJE site :

When Nazi saboteurs attack Camp Lehigh, their explosions cause turmoil in The World Below. Good Queen Medusa leads a troop of her Sub-Earthmen, riding giant worms, to the surface to investigate, but a final shock seals the shaft behind them. Somehow, the "top-men" (us) misunderstand the intentions of cavemen mounted on giant worms, and Cap has to intervene to prevent a mutual massacre. But a Krimson Klansman calling himself The Spook tells Medusa how she can have revenge on the top-men. Cap has to stop the fatal misunderstandings which ensue, and The Spook is revealed to be one of the saboteurs who caused the whole thing. Pow, right in the kisser! (And, yes, the Sub-Earthmen are still stranded at the end of the story.)