Four years after the disaster at Jurassic Park, chaos theorist Ian Malcolm finds out that there's another island, Isla Sorna, where dinosaurs have been thriving in the wild, unbeknownst to the public. This location, Site B, was the breeding ground for the creatures now inhabiting the abandoned theme park. Malcolm learns of it when approached by John Hammond, who has lost control of his company, InGen, to his nephew, Peter Ludlow. Hammond invites Malcolm to join a research team set to document the dinosaurs, in order to rally public support for making the island a protected nature reserve. Initially resistant due to his previous experience, Malcolm changes his mind when he discovers his girlfriend, paleontologist Sarah Harding, is already there.

Malcolm arrives on Isla Sorna with equipment specialist Eddie Carr and documentary producer Nick Van Owen to find Sarah. However, they soon learn they are not alone; another InGen team led by Ludlow and guided by the skilled hunter Roland Tembo has arrived with the aim to capture the dinosaurs and bring them back to the mainland for a new Jurassic Park in San Diego. As two groups with opposing agendas explore the dangerous island, they encounter a variety of dinosaurs, including the formidable and intelligent Velociraptors, peaceful herbivores, and the terrifying Tyrannosaurus rex, leading to a struggle for survival amidst the prehistoric inhabitants.