The Lost World is a 1992 film, based on the book of the same title by Arthur Conan Doyle.
It is approximately 1912. Junior reporter Edward Malone (Eric McCormack) bungles into the office of Gazette editor McArdle looking for an adventurous assignment (but no mention of Gladys Hungerford) and is sent to interview Professor Challenger (John Rhys-Davies), whose housekeeper warns Malone about her employer. Malone poses as an Italian scientist, but Challenger sees through it, reveals him to be a Canadian journalist, and wrestles him down a flight of stairs where a policeman awaits. When Malone decides not to press charges, he wins Challenger's respect, and the professor shows him back into his study.
Challenger then shows Malone the sketchbook of explorer Maple White, showing pictures of a cliff —"That, my young friend, is the Lost World"—in Central Africa, and of a creature that looks like a pterodactyl but which Challenger calls a "beast." Challenger recounts his visit to the dying Maple White, including his own near-fatal stabbing by the treacherous Pedro which kept him from any more than a glimpse of the "lost world," and invokes mocked prophets—"Galileo, Darwin, Challenger!"—since the British scientific community does not believe his claims. He decides to dare them all at a meeting later that day.
Challenger interrupts a ceremony honoring Professor Summerlee (David Warner) to gather a group to journey to prove his claims. Malone volunteers, Summerlee agrees to go as long as Challenger does not, and a newsboy Jim (Darren Peter Mercer) and woman Jenny Nielson (Tamara Gorski) volunteer but are laughingly dismissed. Jenny turns out to be a wildlife photographer and daughter of rich American contributors to the sciences, and ends up going when she funds the entire expedition. Her animal rights sensibilities are sneered at by Malone as "zebras" rights. Jim stows away, while Challenger suddenly appears at a native village after Summerlee discovers that the "map" he was originally given is blank.
After they are joined by a female guide, Malu (Nathania Stanford), the six row for weeks, then land and hear native drums. When they reach a sheer cliff face, most are awed, but Summerlee, still skeptical, rejoins, "We've all seen igneous extrusions before." Challenger's old native friend Pujo appears, but another of the party, Gomez, turns out to have been the brother of the thief Pedro who tried stabbing Challenger and was in turn killed. For vengeance, Gomez yanks down the rope used to haul the six onto the cliff plateau so that there is no way back down.
On the trek the expedition sees a white peacock and then apatosaurs. Summerlee falls through the ground into a cavern serving as a pterodactyl rookery. He is attacked but is hauled out of the hole. Jenny grows jealous of Malone's interest in Malu. Jim climbs to a high spot to get the lay of the land and sees a lake and a native with skeleton paintwork. At night he tries to sneak off to the lake, but Malone catches him. Malu also is out walking and the three walk to the sulfurous lake. A "man eating dinosaur" approaches, but Malu hands around a kind of fruit, which they all wipe on their faces. The dinosaur smells them but loses interest.
In the morning the three find that the camp has been attacked and the others are gone. They follow tracks to a gathering of skeleton-painted tribesmen, where they discover the natives have a ritual whereby humans—normally other tribesmen, but this time including the captured explorers—are sacrificed off a cliff to the carnivorous dinosaurs. Jim fashions a "balloon from the gods" with Malone's coat which diverts the tribe long enough for a rescue of the explorers and other captured natives, and they retreat to the safety of a nearby tribe. The natives tell the story of the splintering of the tribe long ago when the medicine men convinced some to worship the carnivorous dinosaurs, the "meat-eaters, evil ones."
Summerlee's extinction theories regarding microbiology help save a baby pterodactyl when he realizes that the plant-leaf garlands involved in the ritual sacrifice contain the antidote to a prehistoric plague. Irrigation and horticultural benefits to the tribe from the explorers follow. After the skeleton tribe's leader is hit with a rock and killed, the tribes reunite. The chief offers the explorers a reward for their service, and they ask for a "way back to our own world." A hidden cave is revealed by the chief, but only after he asks for a promise from all six that they will come back if they are ever needed. They vow to.
At the river, the party finds that their native guides have left, with only Pujo remaining. Then Gomez appears, and shoots at Challenger. Malone saves the professor in the ensuing melee, and Gomez is shot and wounded. Instead of killing Gomez, Challenger decides to leave him behind, saying, "Let the jungle have him." Malu stays in Africa, and Jim leaves with an unusually large backpack.
Back in London, the Royal Zoological Society declares at a meeting, where they decide that, despite Challenger and Summerlee's reconciliation, their tale has insufficient evidence. Fortunately, Jim brought back the baby pterodactyl, and applause and congratulations follow. At a celebration toast, Jenny is complemented for her "transformation" from an African explorer to a British lady, wearing a dress and an emerald Malu gave her. They drink to "science and adventure."
Malone, Jenny and Jim visit the zoo where the pterodactyl, which they have named Percival (or Percy), is being kept. He seems unhappy, so they release him and he flies off, presumably back to "the Lost World."