Four years after the events on Isla Nublar, an upper-class British family docks their yacht ashore at the nearby Isla Sorna, unaware that the island contains genetically engineered dinosaurs. Their daughter wanders off to a nearby jungle, where she is attacked by a group of Compsognathus, but is saved by her father and yacht crew.
An ailing John Hammond invites mathematician Dr. Ian Malcolm to his residence to discuss the recent incident. Hammond's company InGen, which created the dinosaurs, is now headed by Hammond's nephew Peter Ludlow, who used the incident to wrest control of the company from Hammond. Ian learns that InGen had originally created the Jurassic Park dinosaurs on Isla Sorna but the island was abandoned during a storm and the animals were released into the wild to fend for themselves. Ludlow now wants to exploit the island's creatures to save InGen from bankruptcy. Hammond asks Ian to join a team who will document the dinosaurs in their natural habitat, in order to encourage a policy of non-interference. Ian's girlfriend, paleontologist Dr. Sarah Harding, was hired and is already on Isla Sorna. Upon learning this, Ian reluctantly agrees to go to the island, but only to retrieve Sarah.
Ian travels to Isla Sorna with Eddie Carr, an equipment specialist and engineer, and Nick Van Owen, a video documentarian and activist. Ian is shocked to find his daughter Kelly stowed away with them in the trailer which serves as their mobile base on the island. Later, they also find Sarah amidst a herd of Stegosaurs, but she is insistent on staying to continue her research. The group discovers that Ludlow is also on the island and capturing large numbers of dinosaurs with help from teams of mercenaries, hunters and paleontologists, including big-game hunters Roland Tembo and Ajay Sidhu; Roland's second-in-command, Dieter Stark; and paleontologist Dr. Robert Burke.
Malcolm's group learns that Ludlow and the InGen team are planning to ship the captured specimens to an unfinished Jurassic Park attraction in San Diego that Hammond abandoned in favor of the park on Isla Nublar. Nick and Sarah free the captured dinosaurs, who wreak havoc across the InGen team's camp. On the way back to the mobile base, Nick rescues an injured Tyrannosaurus rex infant that Roland hoped to use as bait to hunt its male parent. Nick and Sarah treat the infant for a broken leg, but the Tyrannosaurus adults arrive. They reclaim their infant, destroy the trailer, and devour Eddie during his attempt to rescue the occupants.
Ian and his group are rescued by Ludlow's team. They are forced to work together after losing all their communications equipment. They decide to walk en-masse to a distant abandoned InGen site to call for help. During a break, Stark goes into the wilderness alone to relieve himself and is killed by a group of Compsognathus. After the team sets up a camp for the night, they are ambushed by the Tyrannosaurus adults: Burke is devoured, and everyone else flees into a field of long grass containing a pack of Velociraptors, which kill Ajay and others.
Ian, Sarah, Kelly, and Nick manage to reach the InGen base, ward off more Velociraptors, and successfully radio for helicopter extraction. After being rescued, Nick reveals that he stole Roland's ammunition to prevent him from killing his intended trophy, but they learn that Roland subdued the male Tyrannosaurus with tranquilizers instead. While more InGen personnel arrive on the island to secure the male and the infant for transportation, Roland declines a job offer at the San Diego park from Ludlow, reflecting on Ajay's death and questioning the morality of Ludlow's scheme.
Later, Ian and Sarah attempt to meet with Ludlow in San Diego to convince him to abandon his plans, only for the ship carrying the male Tyrannosaurus to suddenly crash into the docks. The crew is found to have been killed. The male T. rex is accidentally released and goes on a rampage in the city. Ian and Sarah learn that the infant was taken directly to the planned theme park. They retrieve it and use it as bait to lure the male back to the docks, where Ludlow is cornered by both dinosaurs in the cargo hold of the ship; he is then crippled by the adult, and mauled to death by the infant. Sarah uses a tranquilizer gun to sedate the male, while Ian seals the cargo hold doors and police arrive to secure the scene.
In the aftermath, with both dinosaurs on their way back to Isla Sorna, Hammond appears in a televised news interview to announce that the American and Costa Rican governments have declared the island a nature preserve.
Jeff Goldblum as Dr. Ian Malcolm
Julianne Moore as Dr. Sarah Harding
Pete Postlethwaite as Roland Tembo
Arliss Howard as Peter Ludlow
Richard Attenborough as John Hammond
Vince Vaughn as Nick Van Owen
Vanessa Lee Chester as Kelly Curtis
Peter Stormare as Dieter Stark
Harvey Jason as Ajay Sidhu
Richard Schiff as Eddie Carr
Thomas F. Duffy as Dr. Robert Burke
Joseph Mazzello as Tim Murphy
Ariana Richards as Lex Murphy
Camilla Belle as Cathy Bowman
the second installment in the Jurassic Park franchise and the second film in the Jurassic Park trilogy. A sequel to 1993's Jurassic Park and loosely based on Michael Crichton's 1995 novel The Lost World