Collects Original Hulk vs. Iron Man #1-4 (aka Original Sin #3.1-3.4). Following the events of Original Sin, an explosive secret about Marvel's not-so-jolly Green Giant is revealed! What is Hulk's earth-shattering secret? And why is Tony Stark so concerned about Bruce Banner's transformation into Hulk? Everything you know about Hulk's origin story will be challenged here!