White seeks out his friend, George Challenger, giving an account of his adventures, proposing a further expedition to fully explore the plateau.

In London, Challenger organises a lecture in an attempt to convince his colleagues, Professor Summerlee and Lord Thomas, to finance the further expedition with the goal of proving dinosaurs exist on the plateau.

Oscar Perreault, a spectator at the lecture, proposes to pay for the expedition's expenses if the scientists capture a living dinosaur and sends his associate, John Roxton, to represent his interests.

En route, their transportation suffers a breakdown and the journey continues on foot, after which one of the guides is killed by a prehistoric insect.

A second larger cave is then discovered, where Roxton attempts to explode a dynamite charge to kill the team and escape alone; he is foiled by Challenger, however.