During World War II, Steve Rogers, a frail man from Brooklyn, is transformed into the super-soldier Captain America to aid in the war effort. He must stop Johann Schmidt, aka Red Skull, Adolf Hitler's ruthless head of weaponry, and the leader of an organization that intends to use a mysterious device called the Tesseract as an energy source for world domination. Rogers teams up with British MI6 agent Peggy Carter, and after undergoing the super-soldier treatment, he becomes taller and more muscular, equipped with a circular shield made of vibranium.