Yinsen was captured by the local branch of an international terrorist group called "The Ten Rings" sometime before the film and the rest of his family were killed. Yinsen meets Tony again when he was gravely injured by shrapnel and kidnapped by the group. Yinsen constructs a makeshift electromagnet, powered by a car battery, which he implants into Tony's chest as a way to prevent the remaining shrapnel from entering his heart and killing him. Under captivity, Tony and Yinsen are ordered by the terrorists to build a missile similar to the kind Stark was demonstrating to the US military or they will be killed. However, both men know that they will be murdered either way and plan an escape instead.
Yinsen assists Tony in secretly creating his prototype Iron Man armor as a means of escape and also helps Tony to build a prototype power source for the electromagnet that was more powerful and compact. While working together the two men bond. When Tony asks about Yinsen's family, Yinsen merely notes, "I will see them when I leave this place". Yinsen also points out the damage wreaked upon the region by the terrorists, using Tony's own weapons, and ask if this is what he wishes "the legacy of the great Tony Stark" to be.
When the armor was finally completed, Yinsen helps Tony into the suit and preps it for activation. However, when the terrorists get wind of their plan, Yinsen realizes that they need more time for the suit's software to fully load. In order to buy Tony extra time, Yinsen grabs an sub-machine rifle and chases the terrorists away from their workshop but quickly finds himself surrounded and out-gunned. When the suit is fully powered up, Stark easily fights his way through the cave, but finds a gravely wounded Yinsen lying near the entrance. With his dying breath Yinsen explains to Tony that his family had already died and that he was now going to meet them. When Tony thanks him for saving his life, Yinsen reminds Tony: "Don't waste your life," then dies, and an enraged Tony destroys the terrorist camp and their stockpile of Stark Industry weapons before escaping. Yinsen's words and actions were a turning point in Tony's life, as he stopped producing weapons upon his return to the US and became Iron Man.
