Maya Hansen explains Tony Stark about Extremis: It is a "Super-Soldier" solution, in part of her invention. A bio-electronic serum which reconstructs the human body, enhancing with better organs. The assimilation phase is terrible, lasting a few days. But the end result is fantastic, creating a super human being.
Stark is told who got the stolen serum, shares the data with the authorities, and (after dispatching Maya gently) goes after the terrorists as Iron Man.
Before striken by Iron Man, Madden Mallen remembers when as a kid, he saw the Feds attack his home and kill his family. Iron Man finds Mallen's van and attacks it. But Mallen defeats him rather easely (causing Tony serious wounds), and lifts an occupied car to smash him.