In the midst of the American Civil War, a young Union Army officer, Colonel Robert Gould Shaw, is given command of the 54th Massachusetts Volunteer Infantry, one of the first all-Black regiments in the United States Army. Despite the skepticism and racism prevalent within the military and society, Shaw embraces the challenge, driven by his sense of duty and moral conviction. He and his second-in-command, Major Cabot Forbes, begin the arduous process of training and preparing their men for battle, all the while navigating the complex social dynamics and prejudices of their time.

The newly formed regiment is comprised of a diverse group of African American men, including an escaped slave with a fierce thirst for retribution, an educated free man seeking to prove his worth, and a gravedigger looking for a better future. Together, these men face not only the dehumanizing prejudices from within their own army but also the harsh realities of war. As they contend with unequal treatment, including lower pay and substandard equipment, they strive to prove their valor and earn respect as soldiers. Their journey takes them from the training camp to the harsh realities of the battlefield, where they must come together as a unit and confront their own fears and insecurities while forging a new sense of brotherhood and purpose.