It all begins with Captain America shooting a terrorist dead in a bid to save the lives of a bunch of hostages. This single moment of necessary force leads to public unease in the nation's symbol as sees rise to a series of new super soldiers who believe themselves fit to replace Captain America; in the shape of the Super-Patriot, Nuke and G.I. Max.
At the same time the US Government discovers the secret identity of Captain America and subsequently declare the costume, shield, and very symbol that is Captain America as government property. In order to retain the persona of Captain America, Steve Rogers was ordered to serve as a government agent answering only to the Higher Commission, a group of suits in charge of super human activities.
With the United States being a free country, Rogers envoked his right to choose and after 24 hours gave up the uniform and shield of Captain America. The Commission appointed a new Captain America; the Super-Patriot who had recently saved Washington from a serious terrorist attack. After several weeks, Rogers emerged as "The Captain" and armed with a Vibranium shield provided by Stark Enterprises. The Captain and a group of his close friends work together to continue to save the world from threats. A large interlude of the story, ties in with Armor Wars, in which The Captain finds himself at odds with Iron Man.
The new Captain America begins to slip up and things only get worse when his parents get caught in the line of fire. The increasingly unstable Captain America begins a murderous rampage which eventually leads to the confrontation we've all been waiting for: the Original Captain America vs. the New Captain America!