Wyatt Earp, famous lawman, has decided to retire in the wake of losing his brother Virgil in a train robbery. Doc Holliday, Wyatt's former partner and best friend, convinces him to start his own small casino, the AOK, in the last boomtown in America – Las Vegas. Bringing with them Wyatt's brother, Morgan, and Doc's girlfriend, Kate, everything looks to be coming up roses...until Flynn, the biggest billionaire in Vegas, arrives with a private security group, the Pinkertons, headed by one Alan Pinkerton, to back him in "suggesting" that Wyatt should pay them for protection.
Morgan, outraged by this, decides to go on a heist with famed criminal Jesse James, a modern day Robin Hood who steals from the rich to give to the poor after taking his cut, of course. He is captured by the Pinkertons and interrogated, but escapes back to the AOK where Flynn and the Pinkertons pursue him.
In a final battle in which Morgan is killed and the AOK is set ablaze around them, Wyatt rips the shirt from Alan Pinkerton only to recognize the tattoo on his chest...Pinkerton was the mysterious train robber who killed his brother, Virgil.