Strange things are happening in remote areas of Costa Rica. A patient who appears to have been mauled is flown into a medical facility. He speaks the word "raptor" before he finally croaks. Elsewhere, a young girl is attacked by the three-toed lizard that walks like a bird. Researchers who examine the incident are puzzled. What the heck kind of lizard is this?
In Montana, Dr. Alan Grant and Dr. Ellie Sattler are invited by billionaire John Hammond to visit an island he owns. There seems to be some trouble there, and the EPA has gotten involved. Hammond wants Grant's and Sattler's opinions, and he'll pay handsomely for them.
Grant and Sattler agree to come and are joined by Donald Gennaro, a lawyer associated with Hammond, and Ian Malcolm, a quirky mathematician who's way into chaos theory.
So, what's going on? Lewis Dodgson of Biosyn sure knows. Hammond has cloned dinosaurs, and Dodgson wants to steal some embryos so that his company can compete with Hammond's InGen corporation. He has someone on the inside to do the job.
Grant, Sattler, Gennaro, and Malcolm arrive at the island. There they meet Ed Regis, Hammond's Public Relations guy, and Tim and Lex, Hammond's young grandkids.
And then they see some real, living dinosaurs. Cloned, but still.
The group goes on a tour, seeing where the dinosaurs are genetically engineered, hatched, and raised. They meet the chief geneticist, Dr. Henry Wu. They then visit the control room, meeting computer genius Dennis Nedry, chief engineer John Arnold, and park warden Robert Muldoon. Next they stop by the cage housing the Velociraptors. The animals carry out a coordinated attack, fortunately obstructed by an electric fence.
The tour through the park starts off okay, all things considered, but the group soon determines that some of the dinosaurs are breeding. Grant finds a Velociraptor egg near a sick Stegosaur that's being tended by the park's vet, Dr. Harding. Malcolm tells Arnold to set the park's search monitors to look for and count more than the expected number of animals. Sure enough, several of the species are breeding.
Sattler and Gennaro stay with Harding while the rest of the group returns to the tour. Nedry shuts power down so that he can steal some embryos, and, well, this allows some of the dinosaurs escape. On the way out of the park, Nedry gets lost in the rain and becomes dinner for a hungry dino.
Lesson: don't steal dinosaur embryos.
The adult Tyrannosaurus rex attacks the tour cars. Regis flees, abandoning the kids. The T. rex tosses the car the kids are in into a tree. Malcolm runs, but the T. rex gets him before he gets far and tosses him into the air. Grant escapes and finds the kids. Regis gets gobbled up by the juvenile T. rex. This is the legit paleo diet, folks.
No one in the control room knows about the escaped dinosaurs or the attacks. Muldoon discovers a Jeep is missing. Yeah, the Jeep that has his gun in it. Oops. This is where Seinfeld would angrily say, "Newman"—or, sorry, "Nedry." Same actor.
With control in a panic, Arnold calls Harding back. Muldoon and Gennaro head out to rescue the others. They discover hints that Grant and the kids are still alive. They find Regis's leg—ew—and the injured Malcolm.
Arnold tries to piece together Nedry's programming so that he can restore the system. Grant, Tim, and Lex find shelter and sleep—because bedtime routines are important for kids, no exceptions. And Grant is tired. He's forty, guys. That's old. Ish.
Moving on: Muldoon goes out to repair the damaged fences, but he soon has a bigger problem. The T. rex has got into the sauropod paddock.
While sleepy-eyed Arnold is trying to reboot the system and get the phones back online, well-rested Grant guides the kids through the park. They see some friendly dinosaurs, but then the T. rex spots them while they're on a raft. They're almost killed, but they escape when the juvenile T. rex distracts the adult one by trying to claim its meal. The enemy of my enemy…
Arnold finds Nedry on the monitors. Muldoon gets his gun, but he leaves Nedry's body. No time for a burial. They're all a tad miffed at the computer guy, anyway.
Grant, Lex, and Tim enter the aviary. They're attacked by Pterodactyls, but they escape. Muldoon tries unsuccessfully to tranquilize the T. rex. Meanwhile, Malcolm predicts further disaster.
The kids and Grant fall down a waterfall, once again meeting the Tyrannosaur. Tim is almost eaten by the beast, but he's saved when the tranquilizer dart finally goes into effect. Grant discovers an electric car. Oh, yeah. The tables have turned, dinos.
Things are looking up, but then the system goes down again. Zombie Nedry? No, it turns out the park has been running on auxiliary power since the reboot, and none of the fences have been electrified this whole time.
And the raptors are loose. And they're ready to party like it's 1999.
Muldoon takes charge, ordering Arnold to go the maintenance building to restore the main power, Wu to stay in the control room to reboot the system, and everyone else to go to the lodge. He and Gennaro go out to distract the raptors so that Arnold can make it to the maintenance building alive.
The raptors take the field and score a first victory. Arnold is killed. Muldoon and Gennaro are injured. The raptors get on to the roof above Sattler, Hammond, and Malcolm. They begin to bite through the bars.
Back at the visitor center, Grant talks to Muldoon on the radio and gets up to speed on the situation. Everything is not awesome. Grant leaves the kids so that he can go help. In the tense climax, Wu is killed, but the others manage to kill the raptors and get the power back on. Tim saves the day with his mad computer skills. Lex doesn't really do anything, but we still like her.
Grant and Sattler go out to the raptor nest to count them. Hammond takes an ill-timed stroll, hurts his leg, and is killed by compys. The Costa Rican government shows up, rescues the survivors, and destroys the island.
The survivors are kept at a hotel for questioning.