Set in the year 1851 in the rugged landscapes of the American West, we follow the perilous journey of two gunfighter brothers, Eli and Charlie Sisters. Hired by a wealthy businessman known as The Commodore, the brothers are given a grim task: to track down and eliminate a man named Hermann Kermit Warm.
Meanwhile, John Morris, a private detective, has been commissioned by the Commodore to locate Warm and hand him over to the Sisters. Morris encounters Warm, who is traveling by a wagon train heading to California amid the Gold Rush, and the two develop an unlikely friendship. Upon arriving in Jacksonville, Morris's dark intentions are revealed to Warm through a set of handcuffs that Morris possesses. However, Warm's instinct to fight back at gunpoint is thwarted as Morris manages to overpower him. Warm discloses his mission to find gold utilizing a unique chemical formula that he has created. The Sisters brothers, sent to retrieve the formula, likely contemplate torturing and killing Warm.
Determined to save an innocent life, Morris makes the critical decision to release Warm, and they venture away from Jacksonville together. As they travel toward San Francisco, Warm reveals his grand ambition to create a utopian society, one free of greed, in Dallas, Texas.
However, the Sisters' quest is soon beset by a string of misfortunes: an aggressive bear mauls one of their horses, Eli narrowly escapes a venomous spider bite, and Charlie struggles with excessive drinking which leaves him in a perpetual state of hangover. Upon discovering Morris's betrayal in Jacksonville, the Sisters pursue Morris and Warm, leading them to Ms. Mayfield's establishment, a hotel and brothel. Although Mayfield insists she hasn't seen Morris and Warm, she warmly receives the brothers. A compassionate prostitute warns Eli of impending danger; despite attempts to flee with a drunken Charlie, they are cornered by gunslingers hired by Mayfield. In a fierce showdown, the brothers eliminate their attackers and, in a brutal turn, murder and rob Mayfield for information about Warm and Morris.
In San Francisco, tension brews between the brothers concerning the hunt. While Eli yearns for retirement, Charlie dismisses this desire with anger. The following day, Charlie discovers a claim staked in Morris's name nearby, prompting Eli to reluctantly agree to pursue Warm as their final endeavor.
On their journey, the Sisters fall into an ambush set by Warm and Morris, prompting an alliance against Mayfield's remaining henchmen, who seek revenge for her death and to claim the formula for themselves. Working together, they defeat the attackers and agree to aid Warm and Morris in their quest for gold in exchange for a share of the profits. The newfound camaraderie blossoms as the men engage in building a dam, a pivotal step towards creating the vision Warm has of a better society.
As the dam becomes operational, Warm explains that his explosive chemical formula, when introduced to water, will illuminate gold ore briefly—though with a perilous side effect. The brothers commence the gold-gathering process, but chaos ensues when Charlie loses control, leading to disastrous injuries for both Warm and Morris.
In the aftermath, Eli rushes Charlie to a nearby town where his severe injuries lead to an amputation. Soon after, hired guns from the Commodore arrive, demanding their surrender—a conflict Eli confronts head-on. Subsequently, Eli and Charlie decide on a dramatic act of vengeance against the Commodore. Upon arriving in Oregon City, they discover that the Commodore has passed away. The brothers pay a visit to his open casket, where Eli delivers a punch to confirm the Commodore's demise. With their mission now concluded, they head home to their mother, who, despite her initial suspicions, opens her arms to welcome them back.
