Stark Arms is the largest arms supplier to the US military worldwide. Its new head, Tony Stark (Robert Downey Jr.), is suave and talented. He works closely with the company's veteran Obadiah Stane (Jeff Bridges) to push Stark's business to the top. In real life, Tony is keen on collecting luxury sports cars, making some inventions, and of course, a romantic relationship is indispensable. Fortunately, he has a good assistant like Virginia Potts (Gwyneth Paltrow) who takes care of everything carefully, so that he can live a free and easy life as a nobleman. On the way to the Middle East to show the military new weapons, Tony and his group were attacked by terrorists. He was hit by shrapnel and almost died. With the help of Dr. Inson, Tony transplanted a nuclear-powered artificial heart into his body. The terrorists asked Tony to make a powerful weapon of mass destruction. He and Inson pretended to be friends and secretly made a set of steel armor powered by fusion energy. After wearing the armor, Tony made a big fuss in the terrorists' base, and improved it after returning to the United States. However, he didn't know that there was a darker conspiracy waiting for him...