In the mid 1870s, outlaws Jesse James, Cole Younger and their brothers are granted amnesty by the Missouri legislature, sympathetic to the troubles created for all citizens by the American Civil War. The bankers victimized by the James and Younger gangs are vehemently opposed to this action and hire a Pinkerton agent to follow the outlaws' every move.
Younger has put aside plans to rob a bank in Northfield, Minnesota, said to be the largest west of the Mississippi River. The job appeals, however, to Jesse and Frank James, who have no intention of changing the way they make a living.
Cole is ambushed by the Pinkerton's agent men, who use a prostitute as bait. And when the bankers succeed in overturning the amnesty by bribing the politicians, Cole travels by train to Minnesota to check out the bank.
Once there, Cole discovers that townspeople are unwilling to risk placing their money in the bank owing to concerns over its safety from thieves. Jesse, Frank, and their men arrive on horseback and, together with Cole, persuade the locals that a gold shipment is on its way to the bank because it is supposed to be the safest possible place for it.
Once the citizens begin banking their money, the robbery commences. Many things go wrong, though, including one outlaw being locked inside a vault, and two members of the gang are killed by the townspeople. Cole Younger and his men flee to a nearby farm, but a posse tracks and apprehends them. The James brothers get away. But when Jesse mentions to Frank his intention to permit Bob Ford to join the gang back in Missouri, his fate is sealed.