Widower Henry and his son Wyatt live a modest life on their farm in Oklahoma Territory in 1906, with their uncle Al nearby. Frustrated by the monotonous life of farming, Wyatt's curiosity is piqued when they discover a bloodied, lost horse. Their investigation leads them to a gravely injured man named Curry, who bears a gunshot wound and a satchel full of cash. Initially hesitating, Henry decides to help Curry, taking him to their farm to treat his injuries, while also interrogating him about his past. Curry claims to be a lawman and the lone survivor of a deadly encounter with outlaws.
As Henry secures Curry, he leaves to fetch a doctor. During this time, Wyatt sneaks into Henry's room and finds documents that spark his interest but also leads to Curry's escape. In a moment of chaos, Curry overpowers Wyatt just as Henry returns to save his son. Shortly after, a trio led by Ketchum arrives at their farm, insisting they are lawmen in pursuit of Curry. Their suspicious behavior raises Henry’s doubts about their legitimacy.
In a pivotal conversation later, Curry divulges personal knowledge that deepens Henry's trust in him. He soon narrates his harrowing experience witnessing the infamous Billy the Kid's death. Their shelter is unexpectedly attacked by Duggan, one of Ketchum's men, leading to a brutal confrontation where Henry showcases his survival instincts by strangling Duggan in the mud, with Wyatt witnessing the ordeal.
The next day, Ketchum makes a return, now with his gang, vastly outnumbering Henry, Wyatt, and Curry. Curry urges them to surrender, but Ketchum forces Henry’s hand by coldly executing Al. Enraged, Wyatt retaliates. As Henry gears up, he utters words reminiscent of Billy the Kid, prompting Curry to realize that Henry is actually Billy, the notorious outlaw who is alive after faking his own death with Pat Garrett's help.
In a dramatic turn, Henry pretends to comply but quickly fights back, taking down several of Ketchum's gang members before escaping through the back. With only a few adversaries left, Henry outsmarts Stilwell, the gang's tracker, before another confrontation with Ketchum reveals the villain’s resilience. The fight is fierce, but Henry ultimately emerges victorious, shooting Ketchum in the head.
Just when things seem to settle, Henry notices a brand on Curry’s arm, leading to a shocking betrayal as Curry shoots him, confessing to his own corruption and previous alliance with Ketchum. Just as Curry prepares to kill Henry, Wyatt returns at a critical moment, shooting Curry and saving his father. In a touching farewell, Henry imparts wisdom to Wyatt, acknowledging the changing world around them and hoping his son will carve out his own path. Tragically, Henry dies in Wyatt's arms.
In the aftermath, Wyatt buries his father beside his mother and sets off on a new journey, equipped with cash, two horses, and cherished memories.
