Secret Avengers #16
RUN THE MISSION! DON'T GET SEEN! SAVE THE WORLD!
A secret city buried one mile under American soil is discovered through the leakage of Von Doom radiation - a type of energy emitted only by time-travel devices. So the Secret Avengers head underground to a weird metropolis forgotten about for decades, because a time machine in the wrong hands is the worst kind of WMD imaginable. Master storyteller Warren Ellis begins his tenure on Earth's Mightiest Clandestine Super-Team, illustrated by Eagle Award-winning Jamie McKelvie.