After a business trip, Scrooge McDuck aboards his plane back to Duckburg alongside Donald. In the plane, Scrooge tells Donald he intends to buy an improductive land because Gyro Gearloose found there's uranium, and nobody else knows. However, the plane crew are the Beagle Boys in disguise, who leave Scrooge and Donald stranded in an island so someone else can win the land auction. They also leave Donald's luggage, not knowing it has his Duck Avenger equipment.
While Scrooge isn't watching, Donald uses the ultrasonic tele-brake to stop the plane and make the Beagle Boys return to repair the motors. Then Donald puts Scrooge's fedora on his eyes so Scrooge cannot see him using his special jumping boots to jump onboard the plane and become the Duck Avenger.
The Beagle Boys call their boss and are instructed to jump to a speedboat and leave the plane to sink. The Duck Avenger, who had fallen asleep, awakes and uses the red part of his pen to cut an exit and get out just in time. He uses his luggage as an improvised boat and a spray to impulse. When the spray is over, the Duck Avenger throws it away and it's caught by a playful dolphin who brings the Avenger to the Duckburg beach.
The Duck Avenger goes to Scrooge's house and despite several clumsy mistakes, reaches the office room where he finds a microphone in the telephone, so Gyro's call was wiretapped and somebody else knows about the uranium. The Avenger decides he will find the mastermind during the auction.
The following morning, John D. Rockerduck is about to buy the land on twenty thousand when somebody offers twenty millions, and Rockerduck is surprised to see Scrooge. Rockerduck nags the Beagle Boys for not leaving Scrooge at the island and sends them to their hideout without dessert nor TV. "Scrooge", actually Donald in disguise, is worried as he doesn't know where was the island to rescue uncle Scrooge, but he gets the idea of having Rockerduck himself guide him there.
The Duck Avenger, disguised as Scrooge again, goes to Rockerduck's house and reveals the wiretapping at his phone. While Rockerduck tells he wouldn't leave Scrooge stranded forever but just a week, "Scrooge" reveals to be the Duck Avenger and having bought the land in Scrooge's name. After the Avenger leaves, Rockerduck calls the Beagle Boys, telling them that Scrooge is still at the island so they will go after him to make him sign a document giving the land to Rockerduck. Luckily, the Duck Avenger has heard everything with his special earplugs and goes to Rockerduck's private airport.
An hour later, Rockerduck and the Beagles get onboard his private plane and reach the island where Scrooge awaits. Rockerduck tells Scrooge to sign or be left living of bread and water, but the Duck Avenger throws a smoke bomb and treathens Rockerduck and the Beagles to remain in the island for a week while he leaves with Scrooge in the plane. The Avenger tells Scrooge that Donald bought the land disguised as him.
The following day, Donald awaits for Scrooge, who is paying the land deed, but when he discovers Donald offered TWENTY MILLIONS, angrily chases him while telling Donald will have to work for free until he gets enough uranium to repay.