Mr. Quincy Magoo, portrayed by the talented Leslie Nielsen, is a prosperous owner of a canned vegetable factory who attends a gala at a museum. During the festivities, his nephew Waldo, played by Matt Keeslar, becomes infatuated with a captivating woman named Stacey Sampanahoditra, brought to life by Jennifer Garner. However, the party takes a turn when jewel thieves Luanne LeSeur, depicted by Kelly Lynch, and Bob Morgan, portrayed by Nick Chinlund, successfully steal the museum’s stunning ruby, “The Star of Kuristan,” before fleeing to their boss, Austin Cloquet, a character played by Malcolm McDowell.
Meanwhile, unaware of the trouble around him, Mr. Magoo and his loyal dog Angus venture out for a fishing trip, crossing paths unknowingly with the thieves. A chaotic confrontation between Luanne and Bob leads to the loss of the stolen ruby, which accidentally lands in Mr. Magoo’s boat without him realizing it. Bob attempts to retrieve the gem but clumsily ends up on a paddle wheel instead.
Consumed by the pursuit of the ruby, the museum’s curator and Stacey enlist the aid of two agents: Gustav Anders from the CIA, played by Ernie Hudson, and Chuck Stupak from the FBI, portrayed by Stephen Tobolowsky. They believe that Mr. Magoo has stolen the precious jewel. Stacey's mention of her opera invitation leads the agents to the same venue where Mr. Magoo is unknowingly caught up in a web of misunderstandings. At the opera, he mistakenly strikes Stupak with a tool, adding to the comedy of errors.
The following day, Luanne cleverly deceives Mr. Magoo into bringing her to his home, pretending to be injured. As Stupak investigates, he stumbles upon Luanne’s fingerprints, leading him and Anders straight to Mr. Magoo’s abode. Bob, on a separate mission, also infiltrates Mr. Magoo's home, ultimately discovering the ruby. However, he is caught during the act and steals Mr. Magoo’s prized Studebaker, prompting a wild chase with Luanne and Mr. Magoo in hot pursuit, using Magoo’s quirky Eggplant-mobile.
Austin is preparing to show off the ruby at an auction for his nefarious associates when Mr. Magoo, attempting to stay incognito by disguising himself as 'Ortega Peru,' finds his cover blown when his tattoo washes away in the pool. Luanne disrupts the auction, snatches the ruby, and makes her escape on a snowmobile. Meanwhile, the authorities arrest Austin and his cohort, while Mr. Magoo takes off on an ironing board, inadvertently crashing into a women’s ski competition.
With the help of Waldo and Angus, Mr. Magoo embarks on a comical yet daring chase to recover the ruby. A disguised Luanne poses as an old woman, and through a series of mischiefs, they follow her to Brazil, where Waldo observes the real Ortega—played by Miguel Ferrer—in action. In a chaotic sequence, Mr. Magoo snatches the ruby during a wedding ceremony, leading to a chaotic chase involving criminals, government agents, and Luanne.
Trapped on a raft heading toward a waterfall, Mr. Magoo ingeniously uses the raft like a parachute to save himself. After a whirlwind of adventurous escapades, Mr. Magoo and Waldo manage to return the stolen ruby to the museum, all while ensuring that Ortega, Luanne, and their accomplices from Brazil are apprehended by the authorities. Ultimately, Mr. Magoo and Angus return home, victorious after their exhilarating quest.
