After failing the rescue attempt of a raccoon in the Himalayas (a parody of the opening to the film Cliffhanger), Ace Ventura undergoes an emotional breakdown and goes on a personal soul-searching quest by becoming a Tibetan monk. He is approached by Fulton Greenwall, a British correspondent working for a provincial consulate in the fictional African country of Nibia. Being that Ace's influence is disruptive to the monastery, the Grand Abbot eagerly gives Ace excuses by which to justify his departure.
Greenwall asks Ventura to find a sacred animal called Shikaka, which has become a point of contention. Shikaka, which is a great white bat, is a sacred animal for the Wachati and Wachootoo tribes of Nibia; whenever its name is spoken, the tribesmen must bow. Accompanied by his capuchin monkey, Spike, Ace travels to Africa and returns to his pet detective work.
After arriving in Nibia and meeting with the head of the consulate, Vincent Cadby, Ace begins learning about his case as well as the possible suspects. Ace, normally an animal lover, must overcome his fear of bats in order to continue studying the case. He travels to the Wachati tribal village, where he learns that Shikaka is meant as a wedding present from the Wachati Princess, who is set to wed the Wachootoo Prince. If the bat is not returned in time, the Wachootoo will declare war on the Wachati tribe instead. Much of Ace's activity involves eliminating various suspects and enduring the problems of dealing with the Wachati and the Wachootoo, who refer to him as the "white devil". This proves difficult, and is made more so by other incidents including attempts to kill him.
Reduced to the limit of his ability to solve mysteries, Ace consults the Grand Abbot via astral projection.
Advised by the Abbot, Ace finally discovers that Vincent Cadby had taken the bat and hired Ace as a cover for his own crimes. Cadby plans to let the tribes destroy each other and take possession of their land, using the numerous bat caves containing guano to sell as fertilizer. Ace manages to thwart Cadby's plans. However, tribal security chief Hitu is by Cadby's side and sends him to jail, but Ace calls an elephant to escape, and then summons herds of animals, crushing Cadby's house. He tries to shoot Ace with a shotgun, but he is knocked out by Greenwall's fist. After waking up, Cadby manages to escape, with the bat, in a car and Ace chases him in a monster truck. Ace throws the truck's cigarette lighter at Cadby in an attempt to distract him, who finally rams into a tree and the cage with the bat flies away. Ace runs over Cadby's car, while Cadby runs away.
Ace, tries to chase him, but when he sees that the sun is rising, he confronts his phobia and dramatically returns the bat to the tribes by running through their battlefield with it clutched in his hands, while screaming its name. Cadby, who was covertly watching, is discovered when Ouda sees him and calls out to alert the nearby warriors that another "white devil" is in the area. He is then pursued by both tribes. Meanwhile, Ace accomplishes his mission when he puts (displeased) the bat in his cage. Cadby, who was pursued, ends up lost, out of sight of the tribes. While he was laughing in safety in a tree, he ends up in the hands of an amorous silverback gorilla. The Princess is married to the Prince, who earlier appeared as a champion wrestler sent to challenge Ace's presence in the tribe. Moments later, it is discovered to the tribes' displeasure that the young bride is no longer a virgin, apparently due to Ace's intervention. Both of the tribes promptly pursue Ace, concluding the film.