Rather than rescuing Professor Xavier, who has been captured by Factor Three, the X-Men have to make a detour to Subterranea. The underground world is home to two villains, Mole Man and Tyrannus. Today's episodes cover their backstories before diving into the villains' conflict with the X-Men in Uncanny X-Men #34.

Issues covered: Incredible Hulk #5, Fantastic Four #1, Tales to Astonish #80-81, Uncanny X-Men #34