Jurassic Park

The park's collapse, which Ian Malcolm predicted from chaos theory, is caused by a combination of sabotage and the animals' own unplanned breeding. Dennis Nedry, bribed by rival geneticist Lewis Dodgson to steal frozen dinosaur embryos for Biosyn, shuts down the park's security and fence systems to cover his theft. He never escapes the island: lost in a storm, he is killed by a Dilophosaurus. With the fences down, dinosaurs get loose across Isla Nublar, including a Tyrannosaurus rex that wrecks the stranded tour vehicles, kills PR director Ed Regis, and badly injures Ian Malcolm. Paleontologist Alan Grant survives with Hammond's grandchildren, Tim and Lex, and the three spend the rest of the crisis making their way back to the visitor center on foot, evading the T. rex, pterosaurs, and eventually a pack of escaped Velociraptors, while Grant pieces together (via a raptor eggshell and a captured raptor hatchling) that the dinosaurs have been breeding on their own, using frog DNA that let some "female" animals switch sex.

Back at the compound, the crisis kills several more of the park's staff: chief engineer John Arnold is caught and killed by a raptor while trying to restore power at the maintenance shed, and geneticist Henry Wu is killed by a raptor while trying to help Ellie Sattler, who narrowly escapes by diving into the swimming pool. Game warden Robert Muldoon survives multiple close calls, including destroying one raptor with a rocket launcher, and lawyer Donald Gennaro also survives, hiding out during the worst of the chaos. Grant, the children, and Gennaro eventually fight off a group of raptors inside the hatchery using a toxic substance, restore power to the control room, and get the phones working again. With Gennaro's warning, the departing supply boat is recalled just before reaching the mainland, and its crew kills the raptor stowaways aboard before any of them can reach Costa Rica.

John Hammond, wandering outside while brooding over the park's failure, falls, breaks his ankle, and is killed and eaten by a pack of small Procompsognathus. Ian Malcolm, gravely wounded from the T. rex attack, dies of his injuries. Grant, Sattler, Muldoon, and Gennaro use the tame raptor hatchling Grant found to track down the wild raptor population and discover a large nest hidden in the park's abandoned waterworks, confirming that the animals have been breeding and migrating toward the mainland coast. Costa Rican and international authorities declare the island a biohazard, evacuate the remaining survivors, and firebomb Isla Nublar with napalm to destroy what's left of the park and its animals.

In the epilogue, weeks later in a Costa Rican hotel where the survivors are being debriefed, Grant is visited by a local doctor, Martin Gutierrez, who tells him that an unidentified pack of animals has been sighted migrating through the mainland jungle — strongly implying that some of the dinosaurs escaped the destruction of the island and are now loose in Costa Rica's ecosystem, leaving the central threat unresolved even after the park itself is gone.

Jurassic Park ends with the island theme park destroyed and most of its senior staff dead, but the danger not fully contained. Key survivors going into the next book: paleontologist Alan Grant, paleobotanist Ellie Sattler, game warden Robert Muldoon, and lawyer Donald Gennaro all make it off Isla Nublar alive. Tim and Lex Murphy, John Hammond's grandchildren, also survive thanks to Grant. Ian Malcolm — the chaos-theory mathematician who predicted the park's collapse — dies of injuries sustained in a Tyrannosaurus rex attack. John Hammond, InGen's founder and the park's visionary, is killed and eaten by a pack of Procompsognathus after breaking his ankle. Engineer John Arnold and geneticist Henry Wu are both killed by Velociraptors during the crisis. Systems engineer Dennis Nedry, who sabotaged the park's security for a bribe from rival company Biosyn (represented by Lewis Dodgson), is killed by a Dilophosaurus before he can deliver the stolen dinosaur embryos.

The park failed because InGen's genetically engineered dinosaurs — created from ancient DNA recovered from amber-preserved insects, with gaps filled using frog and other animal DNA — were designed to be all-female and lysine-deficient so they couldn't breed or survive outside captivity, but the frog DNA allowed some animals to spontaneously change sex, and the dinosaurs bred undetected because the park's monitoring software was set to look for an expected population count rather than actually counting the animals. When Nedry's sabotage disabled the electric fences, Tyrannosaurus, Velociraptors, and other species escaped their paddocks; a T. rex attack stranded the tour group, and a subsequent raptor incursion at the visitor center killed several staff before the animals were beaten back with Grant's help.

Authorities ultimately evacuated all survivors and destroyed Isla Nublar and its remaining dinosaurs with napalm, believing the threat contained. However, before the destruction, Grant, Sattler, Muldoon, and Gennaro discovered a hidden nest showing the raptors had already been migrating toward the coast, and raptor stowaways were found and killed on a supply boat headed to the mainland just before it could dock. In the closing scene, a Costa Rican doctor tells Grant that an unidentified pack of animals has been sighted migrating through the mainland jungle, strongly suggesting that some dinosaurs escaped the island's destruction and are now living wild in Costa Rica. This unresolved thread — dinosaurs loose beyond Isla Nublar, and the fate of InGen's technology and Hammond's dream after his death — is the open situation as the story ends.