While observing the effects of his experimental technologies on the American war effort, Tony Stark is injured by a booby trap and captured by the enemy, who then orders him to design weapons for them. However, Stark's injuries are dire and shrapnel in his chest threatens to pierce his heart. His fellow prisoner, Ho Yinsen, a Nobel Prize-winning physicist whose work Stark had greatly admired during college, constructs a magnetic chest plate to keep the shrapnel from reaching Stark's heart, keeping him alive. In secret, Stark and Yinsen use the workshop to design and construct a suit of powered armor, which Tony uses to escape.