The assertive, arrogant Professor Challenger, a renowned biologist and anthropologist, challenges the London Zoological Society to embark on an expedition to validate his sensational claim that he had discovered living dinosaurs during his previous expedition to the Amazonian basin. Apart from him and his 'socialite' counterpart, Professor Summerlee, the team comprises experienced discoverer Lord Roxbury, young reporter Ed Malone - who was publicly humiliated by Challenger's umbrella upon his arrival - and Jennifer Holmes, the boss of Malone's news agency, essentially as conditions for raising the funds.
In Brazil, they are joined by Jennifer's brother David and local guide Manuel Gomez. They soon discover that the dinosaurs are real and formidable creatures, resembling giant spiders, but lose their helicopter and are desperate for a way down from the isolated plateau. They learn that Roxbury had been aware of the fate of Burton White, an explorer whose diary they find, leading them to presume he is dead in search of diamonds and confirmation of the local tribe being the lethal guardians of the plateau's secrets, but also receive surprising assistance...
