: A young journalist as part of a research expedition finds himself in the mysterious Lost World, which is inhabited by dinosaurs and warring tribes of Indians and human apes.
The young Irishman, Eduard Dan Melone, an employee of the London edition of the Daily Gazette, is in love with the charming Gladys Hunterton. He tries to confess her love, but she thwarts this attempt. The girl dreams of being a wife, a faithful companion and like-minded person of a famous hero, so that a glimpse of his glory also falls on her. Gladys declares that he will give his hand and heart only to such a man.
Having decided to certainly accomplish an outstanding feat, Melone goes to the editor of the "Latest News" department with a request to give him an assignment associated with "adventures and dangers." After thinking, the editor invites Melone to expose one “charlatan, modern Munchausen” and sends the journalist to Professor George Edward Challenger. Some time ago, a professor brought evidence from South America that confirms that prehistoric animals still exist. The scientific community has recognized this evidence as falsified, which terribly angered Challenger. Since then, the professor has savagely attacked anyone who crosses the threshold of his house. Challenger especially hates journalists.
Having introduced himself as an aspiring naturalist, Melone sends a letter to the professor from the address of the journal Nature, in which he asks for a meeting. Soon a response letter comes with an invitation, and Melone goes to Challenger. The professor, a man of short stature with very powerful shoulders, magnificent posture, a huge head, a low, echoing voice and a square blue-black beard, very quickly exposes the imaginary naturalist. There is a fight between him and Melone. It comes to the police, but the journalist refuses to charge Challenger. Having seen in the journalist’s behavior “some signs of integrity”, the professor changes his anger at the mercy and shows the evidence brought by him from the Amazon.
Traveling through the tributaries of the Amazon, Challenger ended up in the village of the Kukama Indians, where a white man, the American artist Maple White, had just died. Among his belongings, the professor discovered an album with images of an unusual plateau and dinosaur, as if drawn from nature. With the help of the Indians, Challenger found this plateau. He could not climb the steep cliffs, but he photographed a pterodactyl sitting on a tree and brought along part of its wing and a huge dinosaur bone. Unfortunately, on the way home, Challenger’s boat turned over, the pictures were hopelessly damaged, and the bones were recognized as a hoax. According to the professor, this isolated plateau arose due to volcanic activity many millennia ago, during the Jurassic period, so prehistoric animals live there to this day.
Having finally convinced Melone of his discovery, Challenger invites him to a lecture at the Zoological Institute, which he intends to attend. In a lecture on the origin of terrestrial fauna, the professor questions the lecturer's words that prehistoric animals have died out long ago. Challenger then offers to verify the validity of his words and send a new expedition to Amazonia. Professor of comparative anatomy Summerly, "a tall, biliary old man," is called to participate in it. He requires Challenger to coordinate the mysterious plateau, but the professor wants younger people to join the expedition, because "the journey will be fraught with many difficulties and dangers." Realizing that he has a chance to become a hero and win the heart of Gladys, Melone jumps up, but he is ahead of the tall, reddish Lord John Roxton, a famous athlete, traveler and hunter. Challenger takes both on an expedition.
After the lecture, Roxton invites Melone to himself to get to know each other better. He gives the journalist a good rifle and tells that he has already been to South America. The lord fought with the Peruvian slave traders, protecting the local peasants, for which he received the nickname "The Beach of God."
Having pledged to send regular travel reports to the newspaper, Melone sets off on a journey. Travelers see Professor Challenger only on the pier, before sending the ship, where he gives them an envelope with coordinates, and demands to open it upon arrival in the city of Manaos on the Amazon, on a specific day and time. From this point on, the narrative takes the form of reports by Edward Melone.
Replacing the ocean boat on the river, the expedition gets to the city of Manaos in the upper Amazon. Despite his age, Professor Summerly is a very hardy traveler. He is convinced that "Challenger is a quack of pure water." Lord John, in turn, believes in the expediency of the expedition and enjoys a journey through his beloved Amazon. Waiting for the deadline set by Challenger, the travelers hire porters: the Negro giant Sambo, two mestizos and three Bolivian Indians. One of the mestizos, Gomez, speaks English. It was his Sambo who once caught listening to the conversations of travelers.
Finally, the time comes to open Challenger's letter, but in the envelope it appears only a blank sheet of paper, which, according to Summerley, confirmed the fraud. At this time, on the threshold of the hacienda, where the travelers stopped, the professor himself appears. In this original way, Challenger joins the expedition and leads it.
Having made a three-day trip on a steam boat up the Amazon, travelers land at an Indian village. Challenger takes from the expedition promise to keep secret the geographical coordinates of the place where they are going. The professor hires two Native American shuttles, in which the expedition travels up the tributary of the Amazon, accompanied by a rumble of native drums: this means that the travelers entered the forbidden territory. All this time, professors have been arguing about anything and behaving like big children.
Finally, the Challenger leads the satellites into the reed channel. Three days later, the duct shallows, and the travelers go on foot. Ten days later, having overcome the quagmire, mountains and endless bamboo thickets, the expedition sets up a camp at the foot of the red rocks of the plateau captured in the map of White Maple. Near the plateau stands a lone cliff, on which Challenger saw a pterodactyl. In the morning, the satellites decide to go around the plateau to find the path by which the artist overcame impregnable cliffs.
On the way, they stumble upon an abandoned camp and find the milestones that Maple White marked his path. In dense thickets of bamboo, travelers find the skeleton of a man of a white race whom someone threw from the top of a plateau. Judging by the remnants of personal belongings, this is an American, the companion of the artist, about whom Challenger heard. Milestone White Milestones lead into the cave. Once there was a passage to the plateau from the cave, but now it is littered with stones. Frustrated travelers leave the cave and are attacked - they are stoned. That same night, a monster attacked their camp in which the amazed Summerly recognized the pterodactyl. The scientist apologizes to his colleague.
Six days later, friends complete a tour of the mountain range, without having found a convenient place to climb. After a little reflection, Challenger finds a way out. He climbs onto a cliff towering flush with a plateau. A mighty beech grows on the edge of a cliff. Travelers chopped it with an ax, and a tree falls across the abyss, forming a bridge. As soon as the four travelers cross the plateau, the half-breed Gomez throws the tree to fall - so he avenges his brother-slave owner, who was killed by Lord John. Gomez does not rejoice in revenge for long - Lord John shoots him with a well-aimed shot. The second mestizo is killed by the faithful Sambo, and the frightened Indians scatter. Then the black man climbs up the cliff and sends his friends provisions and equipment, and he remains in the camp at the foot of the rocks. Travelers are prisoners of an impregnable plateau.
They set up camp under a huge gingko tree, enclose it with prickly branches and call the plateau by the name of its discoverer, the painter White Maple. In the morning, friends begin to explore the surroundings of the camp and soon stumble upon a family of iguanodons. After passing through a dense forest, they find a deep hollow, and in it - a colony of pterodactyls. Professor Challenger inadvertently attracts their attention, and fetid creatures attack the researchers. Lord John has to shoot a gun, but the pterodactyls still manage to injure three travelers. Returning to the camp pretty battered, they discover that someone has been here. An unknown creature entered the fence, descending from the gingko tree, and made a mess in the camp.
Pterodactyl bites are poisonous. Friends spend all day in the camp, and it seems to Melown that they are being watched. Lord John does not stop thinking about the blue clay that he noticed in the nest of flying creatures. At night, a monster will attack the camp, resembling a giant toad with huge fangs. Armed with a burning torch, Lord John drives the monster away from the fence. He does not want to shoot - he is afraid of the noise to attract someone more dangerous. From this moment, travelers do not go to bed without security. In the morning, it turns out that the predatory dinosaur that attacked them tore the iguanodon. Examining the remains, researchers notice an incomprehensible patch of gray asphalt on the skin. Travelers notice the same patches on other iguanodons.
In the afternoon, Summerly raises the question of returning to England, but Challenger refuses to return home without a map of the Maple White Country. It can take months to explore the plateau, but Melone finds a solution. He climbs a gingko tree, one of the highest on a plateau. Climbing to the top of the tree, the journalist stumbles upon a creature with an almost human face that is rapidly escaping. From the top of Melown, you can see almost the entire country with a large lake in the center. Behind the lake you can see a ridge of reddish cliffs with holes in caves. A journalist makes a sketch of a map. The professors allow the young man to name the lake, and Melone calls it “Gladys Lake”.
Excited by the success, Melone cannot fall asleep. He decides to go down to the lake on his own and explore the ridge with caves. Once in the night forest, the journalist is frightened, but goes forward from pure obstinacy. Upon reaching the lake, Melone discovers that the entrances to the caves are lit by bonfires, "which only a human hand could kindle." At the lake, the young man sees many unusual creatures, and among them - a dinosaur painted by Maple White. On the way back, the journalist is haunted by a toad-like monster. Fleeing from a predator, he falls into a trap pit, clearly dug by a man. Having hardly got out of the pit, Melone heads for the camp and suddenly hears a shot. He thinks that his friends are looking for him, but, having reached the place, he finds the camp devastated and empty.
Rushing to the edge of the plateau, Melone sees that one of the Indians has returned, and asks the faithful Sambo to send him for help to the nearest native village. For the rest of the day, Melone unsuccessfully searches for missing friends, and then settles in for an overnight stay in an empty camp. In the early morning, Lord John wakes him up, all scratched, in torn clothes. He grabs a weapon, provisions and takes Melone away from the camp, into dense and spiky thickets. Hiding, Lord John says that the monkeys attacked the camp and wanted to kill them, but, fortunately, Professor Challenger was surprisingly similar to the leader of the human-monkey tribe. The leader took the professor for relatives, and the rest of the animals tied up and dragged into their village. Soon, several short Indians were brought there. Man-monkeys took them to the site near the cliff and, one after another, threw them down. Apparently, this was their usual ritual. Professor Challenger was free to move around the village. He weakened the bonds of Lord Roxton, and he managed to escape. Lord John fears that the man-monkeys will sacrifice Summerly.
Melone and Lord John have time in time. After devastating the ranks of the human apes, they save not only professors, but also the surviving Indians. Having taken the remaining weapons and food from the camp, they take refuge in the thicket, where they spend the night. In the morning, human apes find their refuge, one of the animals attacks Melown, and friends again have to escape. One of the Indians is the son of a leader. He takes friends to the caves where his tribe lives. Travelers are received with honor and signs are asked to help deal with the human-monkey tribe. The next morning, Native American warriors march, using firearms, travelers crack down on the apes, and the females and cubs are taken into slavery.
After the battle, travelers become honored guests of the Indian tribe. Indians respond to requests to show the way to the outside world - they do not want to let go strangers with wonderful weapons. For some time, travelers live near the lake, watching unprecedented animals and eating iguanodon meat, which serve Indians as domestic animals. It turned out that asphalt patches on the skin of lizards are a kind of stigma.
Friends hope for the help of Sambo, who has already sent for help. Challenger, meanwhile, finds a geyser with flammable gas and tries to construct a balloon, while Lord John, putting on something like a wicker basket, visits a nest of pterodactyls. He is still interested in blue clay.
Travelers do not have time to resort to the invention of the Challenger. The leader’s son does not want to keep the people who saved the tribe, and gives them a plan for one of the caves. Friends explore it and find a way out of the plateau. At night, they leave Meple-White Country, taking with them a heavy load. Just at that time, the help promised by Sambo arrives.
Arriving in London, professors speak at a meeting of the Zoological Institute, where they are again ridiculed, and photos brought from a plateau are called fakes. However, this time Challenger has more weighty evidence. A huge box with a live pterodactyl, which was caught by Lord John, is brought into the hall. The lizard begins to fly around the room, people scatter in a panic, and the animal flies out the window. The next day he is seen flying across the Atlantic. Professor Challenger becomes a triumph.
Melone comes to Gladys, counting on reciprocity, and discovers she is married to a "small reddish subject." The journalist is interested in what kind of feat this man performed to win the arm and heart of the impregnable Gladys. It turned out that she became the wife of an ordinary writer from a notary office.
In the evening, friends gather at Lord John, and he shows them a box full of rough diamonds. He was not in vain interested in blue clay - it is this clay that accompanies diamond deposits in Kimberley. Lord John divides the diamonds equally. In return, he wants to organize a second expedition to the Lost World, and Melone decides to join him.
