"Uncle Scrooge: The Grand Canyon Conquest" is the title on the indicia, title page and spine, but the cover title is "Uncle Scrooge: The Grand Canyon Conquest!"
Scrooge is presented with a document by the descendent of a fellow Yukon prospector that makes the descendent owner of half of Scrooge's fortune. Scrooge, Donald and the nephews travel to Hollywood, with Scrooge searching for his old Yukon confederate while Donald and the boys investigate why Scrooge's luxury hotel is suddenly in the red.
Scrooge discovers a pilot who can lead him to Blair Dunwitty's location. However, it involves a perilous journey down the Colorado River through the Grand Canyon, with Owen Dunwitty and his cohorts hot on their tail.
Scrooge enlists Donald as an undercover agent to counter the plans of a master designer who formulates burglary plans and sells them to the highest bidder.
Gyro tries to conceive of an extraordinary invention for the Inventor's Picnic, but is distracted by having to conceive of extraordinary inventions for everyone else.