This takes place in Marvel's Ultimate Universe, which has more hardened versions of familiar superhero characters. Here, Captain America must confront another Super Soldier who is disillusioned with America. In fact, he's supplying North Korea with a Super Soldier formula. This is Frank Simpson, the secret Captain America of the Vietnam War. While the original Captain was missing, frozen after World War II, the government created this new version, though he's also augmented with cybernetics and steroids. This made him crazy and he went missing in '72. What motivates him now is that he wants to teach Steve Rogers a lesson--of what America really stands for, all the bad things the country has done. So Frank kidnaps him and submits him to torture and brainwashing. Will America's icon survive?
I thought this was a great Captain America solo adventure, far more violent and gritty than how we usually see him. Recommended, as is all the Ultimate stories.