In the movie, Steve Rogers undergoes a risky experiment called Project Rebirth, which transforms him into the physically enhanced super-soldier known as Captain America. With his newfound strength and agility, Captain America is tasked with leading a team of soldiers on various missions to combat the enemy forces, including the Red Skull's organization Hydra.
As Captain America battles Hydra operatives and their advanced weaponry, he must also contend with personal struggles, including the loss of his best friend Bucky Barnes and the burden of his newfound responsibilities as a symbol of hope for the Allies.
As the war intensifies, Captain America learns of Hydra's plan to use the Tesseract, a powerful cosmic cube with untold powers, to unleash mass destruction and conquer the world. With the help of his comrades, including agent Peggy Carter and inventor Howard Stark, Captain America must race against time to stop the Red Skull and prevent Hydra from achieving their diabolical goals.
The movie culminates in a thrilling showdown between Captain America and the Red Skull aboard a Hydra aircraft, where Captain America ultimately sacrifices himself to prevent the Tesseract from falling into enemy hands. However, he is later discovered frozen in ice and thawed out decades later in the modern era, setting the stage for his future adventures as a member of the Avengers.