Jackboy was born into slavery on a Barbados sugar plantation. His constant attempts to escape finally pushed the masters too far. They punished the whole family by splitting them up and selling them off. His father's last words had been, "It's okay, son, don't ever give up."
Several years later, wracked by guilt, but still obsessed with freedom, he slips away from a South Carolina tobacco plantation and outsmarts the Confederacy's most vicious slave patrol captain who is hot on his trail. He swims across the Savannah River and taunts his pursuers by hurling obscenities at them from the opposite bank. After days of searching for the safety of Sherman's Army in Georgia, he stumbles across a Confederate soldier behind enemy lines and gets into a life or death fight. A maverick Union lieutenant named Jack Johnson happens upon him just as he is about to bash in the skull of this rebel sniper the officer has been chasing for days.
After taking control of the situation and assuring Jackboy that he is safe, Johnson interrogates the young man and discovers he is remarkably intelligent and resourceful. He takes Jackboy under his wing, enlists him into the army, and teaches him to read, write, and use a gun. Jackboy is beguiled and confused as he witnesses the soft-spoken young officer transform into a cold-blooded battlefield killer with his small squad of seasoned troops wielding sixteen shot Henry repeating rifles. When Jackboy asks him about it, Johnson says, "My folks had money and sent me to war with a dozen Henrys. They told me to use them wisely and not to come home dead. I only hand them out to a few veteran soldiers I really trust. We're usually outnumbered, but we're never out-gunned. I figure the faster we kill them all the safer my men will be." Jackboy embraces the logic and hopes to be in that rare company one day.
Under Johnson's command, Jackboy learns quickly, gets promoted to sergeant, and is allowed to recruit an all-black squad of raiders who fear him more than the enemy. The ex-slave soon becomes a legend to his own people who readily share valuable intelligence about hidden southern resources and troops. On a mission to plunder Confederate assets, they encounter a small band of terrified black men on the run who report that the same depraved slave patrol captain who once chased after Jackboy is now selling hunting trips to southern elites on his nearby estate using captured runaways as prey animals. The next one is scheduled for the following day. They also share a piece of information so shocking that Jackboy keeps it to himself knowing that no white man would ever believe it possible.
When Jackboy reports his findings, Johnson realizes there is no time to seek approval from his commanders or wait for reinforcements. They are the only ones who can prevent the mass slaughter of sixty men, women, and children despite the odds against them. Johnson hands Jackboy one of his spare Henry rifles and says, "You earned it. Kill 'em all and do it fast." Filled with pride, Jackboy replies, "We might be outnumbered, but we won't be out-gunned."
With steely resolve, the small band of Union troops launches a rescue mission to save the sixty doomed slaves and maybe even capture two dozen high-ranking enemy officers and politicians. They know it will be bad when they get there, but what they actually find is worse than anyone could have imagined. Then as a complete surprise, in the heat of battle, Jackboy discovers something he thought had been lost forever and earns personal redemption for what his obsession with freedom had once cost his family.