Still dealing with the aftermath of the Hulk's rampage through NYC, and Giant Man's shocking and vicious attack on the Wasp, the team "welcomes" new members Black Widow, Hawkeye, Scarlet Witch and Quicksilver, and begins to uncover a clandestine alien infiltration of Earth decades in the making - and how it may have began during a secret mission Captain America himself presided over in the darkest days of World War II.