Scrooge McDuck drops by to give Louie Duck some business cards he could use for Louie Inc. Louie explains to Scrooge that he's given up on starting his own company because the line at the patent office was too long (about five people). Beside himself that Louie would give up on his dreams at the first obstacle, Scrooge tells Louie a story from Scrooge's youth.
Scrooge's attempts to find his fortune had taken him to the Wild West town of Gumption, where he was prospecting for a gold nugget. His attempts got his foot stuck under a large pile of rocks. He is helped out by Sheriff Marshall Cabrera, Fenton's ancestor.
Sheriff Marshall tells Scrooge that another prospector has come to Gumption, Goldie O'Gilt. Scrooge angrily confronts her for trying to take the gold when he'd already made a claim for it. The two then get to work trying to beat each other to the gold. They strike it at the same time, but then it's taken by John D. Rockerduck, the new owner of Gumption. Rockerduck claims that as Gumption's owner, he owns any gold in it. Goldie provokes a fight between Scrooge and Rockerduck to distract Sheriff Marshall while she rides off with the gold. Ultimately though, Marshall arrests her and Scrooge.
In jail, Scrooge and Goldie find Gyro Gearloose, who time travelled to Gumption from the future. The three of them convince Sheriff Marshall that Rockerduck is a swindler. He lets them out of jail and teams up with them to take the gold back.
They catch up to the train Rockerduck's leaving town on. Goldie distracts Rockerduck with a musical number while Scrooge takes the keys to the compartment Rockerduck is keeping the gold nugget in.
Meanwhile, Marshall is helping Gyro tinker with a rocket-powered stage coach. An accident with it knocks Gyro unconscious. Marshall improvises a steampunk Gizmosuit out of the remains of the stage coach.
Scrooge and Goldie enter the train compartment the nugget is stored in, but are stopped by Rockerduck's henchman, Jeeves. Scrooge and Goldie are then saved by Marshall in the Gizmosuit. Sheriff Marshall carries the nugget, Scrooge, and Goldie on his back. The suit then runs out of power. Scrooge and Goldie jump off, and Marshall frees himself from the suit just in time before it and the gold fall in the river.
Back in town, Scrooge is dispirited about losing the gold, before realising that the river has carried the gold back to Gumption. Goldie knocks Scrooge out so she can get a head start panning for gold.
In the present, Scrooge asks Louie whether he wants to be a conman like Rockerduck, a shifty operator like Goldie, or a self-made man like Scrooge. Louie then goes to call Goldie for advice.
- David Tennant as Scrooge McDuck
- Bobby Moynihan as Louie Duck
- Lin-Manuel Miranda as Sheriff Marshall Cabrera
- Jim Rash as Gyro Gearloose
- Allison Janney as Goldie O'Gilt
- John Hodgman as John D. Rockerduck
- Keith Ferguson as Johnny, Jeeves, Passenger
- Fred Tatasciore as Town Mayor, Townspeople
- Jennifer Hale as Townspeople