Kelly first appears when she greets her father, Dr. Ian Malcolm, when he is visiting Eddie Carr in his garage where Eddie is modifying the vehicles that are to be used in their expedition to Isla Sorna. Although she insists on accompanying Malcolm on his journey, the destination of which he withholds from her, Malcolm is adamant that Kelly stays with an associate by the name of Karen. After a short argument where Kelly remarks her cut from the school gymnastics team and her feelings on Malcolm often not paying attention to her, Malcolm reports to Eddie, but not before he sarcastically tells Kelly not to listen to him. While Malcolm is conversing with Eddie, Kelly sneaks about the trailers and stows away.
Once on Isla Sorna, Kelly takes the time to make dinner for the rest of the group who are at this point unaware of her presence. However, her campfire alerts the attention of Eddie Carr and Nick Van Owen, the team's video documentarian, who rush to put it with a jug of water before being told to switch to dirt by Dr. Sarah Harding. It is here that Kelly reveals herself and her good-hearted intent to the group. Malcolm is infuriated that Kelly has followed him to Isla Sorna, and after having her clean up the mess she made of the trailer when she was cooking, she points out the sound of approaching helicopters.
Following the rest of the documentation team, Kelly joins the group in watching Peter Ludlow's InGen Harvest Operation chase down and capture several dinosaurs on a Game Trail. Later that evening, she continues to follow as the team track down the InGen Encampment, where she asks why InGen would want to build another Park on Isla Sorna after what Ian told her happened to the Isla Nublar park. Malcolm responds that the InGen team isn't building a Park here, they're taking the dinosaurs off the island. It is here that Nick Van Owen reveals his alternate purpose on the team as a saboteur in the event that Ludlow's team were to arrive. As Nick and Sarah sneak in and sabotage the InGen encampment, Ian and Kelly return to the trailers and Eddie goes to the High Hide.
However, Sarah and Nick return with an injured Tyrannosaurus rex infant and Kelly asks her father to take her somewhere else, fearing that something will hear the infant's cries. Ian takes her to the High Hide, however, once she, Ian, and Eddie are situated, the group notices as a Tyrannosaur walks through the forest beneath them. After receiving no answer from the trailer, Ian gives Kelly his word that he will return once he has sorted everything out. However, the Tyrannosaur parents have come looking for their infant, and after retrieving him, preceded to destroy the trailers and consume Eddie who gives his life to save Ian, Sarah, and Nick.
The InGen Harvest team, however, have come to the rescue and after retrieving Kelly from the High Hide, they return to the InGen camp and from there decide to hike to the InGen Worker Village, where they can radio a distress call.
After a few days of hiking, the people rest for a night in a rocky forest clearing. However, negligence on Sarah Harding's part has left her to remain wearing a shirt that is stained with the blood of the infant Tyrannosaur. The parents have followed this scent trail and the male Tyrannosaur curiously sticks his head into the tent, and sniffs Sarah's shirt, awaking and terrifying the tent's inhabitants: Sarah and Kelly. Helplessly watching in horror as his daughter and girlfriend are subjected to the terror of being awoken by a Tyrannosaurus rex, the situation escalates when one of the hunters, Carter, awakens and screams at the Tyrannosaurs presence. This in turn awakens all the other hunters, who flee. Sarah, Nick, and Kelly leading the exodus with the female Tyrannosaur in pursuit, find a shallow recess behind a waterfall and take shelter.
However, the InGen paleontologist, Dr. Burke, follows them inside and gives away their hiding place to the female Tyrannosaur. Sticking her head into the recess, and terrifying the people inside, she recedes after Burke, who has been frighted away from the recess wall by a harmless milk snake, runs into her mouth and is dragged out of the cave. Malcolm, who had taken shelter under a log when the Tyrannosaurs intruded into the camp, enters the waterfall recess and joins Nick, Sarah, and Kelly.
Now behind the rest of the group, Nick, Ian, Sarah, and Kelly did not fall into the trap set by the Velociraptors in the long grass. However, Ian hears a raptor purring nearby, and is aware that the raptors know of their presence. Sprinting into a different direction than the hunters, the group evades the raptors after falling down a steep, muddy, slope and into the raptors nest, vacant of its inhabitants who are busy devouring their human prey. Nick goes to the Worker Village ahead of the group, who stay behind to let Malcolm rest as he has re-injured the leg that was injured during the Isla Nublar Incident. Once he feels he's ready, Ian, Sarah, and Kelly head to join up with Nick in the Worker Village. By this time, Nick has restored power to the place and has sent the distress call. However, before the rest can meet up with him, Sarah, Ian, and Kelly have been trapped by a trio of
Velociraptors. Barricading themselves inside the Kiln House, Kelly and Sarah try digging their way out, while a pair of raptors dig at the door behind them. However, unbeknownst to them, one of the raptors has gone to where they are digging, and as soon as Kelly attempts to enter the tunnel, the raptor attempts to grab her. Sarah and Kelly then climb up to the building's rafters and once Ian enters the building, he follows suit. However, the raptor had finally been able to wedge himself through the hole and jumped up to the catwalks and cornered Malcolm. Kelly, seeing this, then uses her gymnast skill to kick the raptor through a rotted wood-grated window, and lands safely back in the ground. From here, Sarah orders Kelly and Ian to leave while she handles the last raptor. After climbing into the roof and having the raptor that follows her get into a fight with a fellow raptor, Sarah uses the distraction to rejoin with the group where she, Kelly, Nick, and Ian are airlifted to San Diego. Kelly is dropped off at either Sarah's or Ian's apartment and after an incident involving a Tyrannosaurus loose in the streets of San Diego, is seen watching a CNN broadcast in the apartment.
- Kelly appeared both in the movie and in the novel. However, unlike in the movie, her novel version wasn't related to Ian Malcolm.
- She's the first person in the franchise who killed a raptor with her bare hand, the second being Oscar Morales.