Three youngsters are found bonding with a horse, embodying the early versions of Dudley Do-Right, Nell Fenwick, and Snidely Whiplash. They share their dreams; Dudley aspires to be a Royal Canadian Mounted Police officer, Nell longs to explore the globe, while Snidely thrills at the thought of being the ultimate villain.
Fast forward several years, and their childhood dreams have taken shape. Dudley, now a dedicated Mountie, is often seen following the rules to a fault, completely unaware of his surroundings. Conversely, Snidely has adopted the notorious lifestyle of a bank robber. After orchestrating a heist that pilfers both cash and gold, Snidely deceitfully convinces his gang that he has escaped to the Sudan, leading them on a wild chase while he cunningly disperses the stolen treasure into local lakes. When Dudley catches him in the act, Snidely skillfully misleads him into believing he’s hunting vampires, while he uses similar tricks to scare the horse away.
Just as fate would have it, Nell makes her grand return from her worldly travels and reconnects with Dudley, culminating in a delightful evening spent at a festival hosted by the Kumquat tribe. Meanwhile, the impoverished Kim J. Darling, played by the talented Brendan Fraser, unexpectedly stumbles upon gold in a river, catapulting him into the limelight thanks to Snidely's machinations. This newfound gold rush enhances Snidely's notoriety, and he seizes control over the town, renaming it "Whiplash City," while callously forclosing numerous local mortgages.
As Snidely's past gang members return from their foolhardy pursuit in the Sudan, they intend to take vengeance on him for his treachery. However, Snidely deftly persuades them with promises of opulent living in his newly claimed territory. Sensing something amiss, Dudley confronts Snidely, but is laughed off, and next, Snidely brazenly kidnaps Nell from him. The situation escalates when Snidely sends his right-hand man, Homer, to eliminate Dudley with a bomb; miraculously, Dudley is unharmed when it goes off.
Dudley's predicament worsens when Inspector Fenwick, Nell's father and ally to Snidely, discharges him from the Mounties after learning about his rivalry with Snidely. Overwhelmed with despair, Dudley aimlessly roams the town until he encounters a drunken Kim, who kindly offers him refuge in his cave. Kim reveals Snidely’s schemes and newfound acclaim, eventually escorting Dudley to a Gala Ball in Snidely's honor. Despite Kim's dire warnings about not confronting Snidely, Dudley attempts to regain Nell but ends up failing embarrassingly.
In a twist of fate, Kim’s sympathy for Dudley leads him to devise an intense training program to prepare Dudley for reclaiming Semi-Valley from the grip of Snidely. Dudley’s first move is to terrify one of Snidely's henchmen into revealing the details of an upcoming gold shipment. Disguised as a motorbike-riding vigilante, Dudley sabotages the shipment and leaves his signature on Snidely's workshop and favorite golf course. Unbeknownst to Snidely, who still believes Dudley is enjoying life as a villain, his gang's failures stoke his irritation. As Kim departs to reunite with his family, he expresses gratitude to Dudley for their camaraderie.
In a stunning comeback, Dudley applies his newfound skills to reclaim Nell from Snidely, igniting the latter’s wrath. During a nighttime gathering, Snidely attempts to sway the townspeople to turn against Dudley, only to be met with indifference as they begin to rally behind Dudley’s efforts to restore their town.
As the climax approaches, Snidely learns of Dudley and Nell’s attendance at another Kumquat festival and orchestrates an all-out attack on them. Just when it seems hopeless, the horse returns and assists Dudley in neutralizing Snidely's tanks, leading to a comical showdown where Snidely and Homer inadvertently blast each other. Ultimately, a squad of Mounties arrives to apprehend Snidely and his thugs. Kim also makes an appearance, along with his wife, the Prime Minister of Canada (Sarah Jessica Parker), facilitating the cavalry’s arrival. In a heartwarming conclusion, Inspector Fenwick reinstates Dudley in the Mounties.
The story culminates in a tender moment between Dudley and Nell, seen in their rebuilt home, sharing a loving kiss that signifies their triumph over adversity.
