Captain America as the President of the United States? The Hulk a Microscopic Warlord? Doctor Doom a Hero? Gwen Stacy... alive? Only a few of the dynamic dimensional divergences in the Fourth Volume of Marvel's original alternate earth epics! Featuring the Fantastic Four, the Avengers, the Man-Thing and more! Plus revelations of some of the Marvel Universe's most Eternal secrets! Collects What If? #21-26.