In 1851, Eli and Charlie Sisters, a pair of assassins of minor repute, are hired by a wealthy businessman known only as "the Commodore" to travel from Oregon City to California in order to murder a gold rush prospector named Hermann Kermit Warm, who is described to them as a "thief". Hard-nosed, plainspoken Charlie, more impulsive and aggressive than his older brother Eli, has a fondness for binge drinking and appears remorseless about the crimes he commits. Eli, contemplative and often sentimental, admires and looks up to Charlie but finds himself at odds with Charlie's apparent nonchalance about the directions their lives are taking. The brothers bicker constantly about money, the job, their horses, and each other's personalities.