A mathematician who specialises in Chaos Theory, Malcolm is brought to the Isla Nublar by Donald Gennaro to help judge Jurassic Park. Ian is shocked by the presence of dinosaurs, but states his belief that, no matter what, they are bound to break out and mate as “life finds a way”. While being toured around the island, he flirts with Dr Ellie Sattler, and explains Chaos Theory to her. When Alan Grant and Ellie leave the tour vehicle, after an unimpressive start to the tour, to view a sick Triceratops, Ian states that their random actions are examples of Chaos Theory, before following. While Ellie remains behind with the sick dinosaur and vet Gerry Harding, Ian remains on the tour, discussing relationships with Alan in their vehicle when the tour vehicles are forced to pause. When the fences go down and the Park’s Tyrannosaurus breaks out, Alan attempts to distract if from the vehicle that John Hammond’s grandchildren, Tim and Alexis, are in by waving a flare; Ian does the same, which causes the carnivore to chase after him, but even when he drops the flare it continues chasing him. He is wounded when the Tyrannosaur throws him into the toilet facility; later, Ellie and Robert Muldoon find Ian and rescue him, taking him back to the Visitor’s Center of the Park. Eventually, a bandaged Ian is rescued from Isla Nublar, along with Alan, Ellie, John, Tim and Lex.
While Ian is recuperating in Panama’s Centamcom Base Hospital, he hears that Alan and Ellie have sailed away from Isla Nublar, having gone their to help the army reorganise it; Ian believes that it is another example of Chaos Theory, as it is unknown how they found a boat. A few weeks later, a healed Ian, along with Muldoon, head out to find Alan and Ellie, having heard that they were in the Colombian jungles. They meet in a nearby town, and Ian goes into a deep explanation of Chaos Theory while flirting with Ellie again. When the four leave into the jungle to try and find the Raptors, Ian continues to flirt with Ellie, using Chaos Theory again and again in hopes that it will make Ellie consider a relationship with him. After failing to capture the Raptors, the group scours the jungle by helicopter until they notice a gorilla in the jungle; they land and try to find the gorilla, but it captures Ellie.
Ian, Alan and Muldoon set out to find her, and eventually she runs into them, having escaped the gorilla due to the Raptors. Malcolm sets out with the group, equipped only with a black bag and a gun of undetermined type.The group continue on, and Ian starts to contract a fever, which makes him delirious. This is only worsened when, after having to hide from an attacking BioSyn helicopter, the group encounters a jaguar which attacks and wounds Ian. Luckily, the quartet reaches a Native American village, whose occupants treat Ian. Ellie stays behind to watch over him while Alan and Muldoon leave to try and find rescue. Upon waking up, he and Ellie share a kiss, before setting out to find Alan and Muldoon; they come across the wreckage of two helicopters, which only spurs Ellie on further. Eventually, they find a wall, and Dr Fischer attacks them, wishing to kill the pair. It is then that the Raptors, held captive by Fischer, escape, and kill all of the BioSyn officers before leaving with their chicks. An InGen helicopter then rescues them, and they are shown relaxing with Alan and Muldoon in Caracas, Venezuela. When Hammond gathers a team to send to Isla Nublar to investigate the mysterious events happening there, he forbids Ian to go, due to his recent state of fever.
Eventually Ian Malcolm is summoned by John Hammond to lead a team (with one stowaway) to Isla Sorna to observe and document the animals there before Peter Ludlow and his team go in and round them up. Nick Van Owen and Sarah Harding free the captured animals from Ludlow’s team’s camp, while Nick stumbles upon an injured infant Tyrannosaurus. After bringing the infant Tyrannosaur into their camp from Ludlow’s team, Ian’s base camp suffers the loss of Eddie Carr and the loss of their vehicles. They’re later rescued by Ludlow’s team which make their way to the Operations Center based in the center of the island. Nick Van Owen eventually radios for help and they are all returned to the mainland. Meanwhile Ludlow and his team captured a Male Tyrannosaur and transport it and the infant back to San Diego. When the boat reaches San Diego, it’s found the crew had been slaughtered by the Tyrannosaurus and it unfortunately escapes. Sarah Harding and Ian lure the escaped Tyrannosaurus back to the boat by using the infant for it and the infant to be returned to Isla Sorna. Hammond appeals to the public that the animals require our absence to live in peace.