Iron Man # 1 Vol. 2

"Heart of the Matter"

The criminal organization Hydra attacks industrialist and playboy Tony Stark's research complex in Buffalo, trapping scientist Bruce Banner and head of security Liz Ross with a ticking gamma bomb. Banner tries to minimize the damages by sacrificing his own life, but ends up being transformed into a big green monster, a "Hulk". Tony Stark arrives at the scene and is fatally injured by the Hulk's rampage. He saves his own life in the only way possible – he dons an experimental armor, effectively becoming an "Iron Man".