Nash is one of the mercenaries working for Paul and Amanda Kirby. Following the death of Cooper, who got eaten right in front of the group's plane as it was it was taking off, Nash loses control because Cooper's blood splatters all over the windshield and the plane flies into the jungle, losing its wings before it ends up otherwise mostly intact in the branches of a tree. Everyone survives. Alan Grant manages to quip, "We haven't landed yet" after noticing how high up they are.
Up front with Nash in the co-pilot's seat, Udesky tries the radio, but it's broken, so Paul tosses his satellite phone to them, but for some reason it won't work, either (typical). Amanda sees something through the plane's windshield and screams, but when Udesky and Nash look, it's gone. Suddenly the plane begins shaking uncontrollably.
"Hang on, everyone!" Nash yells, putting the phone in his pocket.
Then the entire front end of the plane is torn away except the pilots' seats, leaving Udesky and Nash sitting in open air and facing the roaring Spinosaurus. They scream and struggle to unbuckle themselves so they can scramble back into the passenger compartment of the aircraft. Udesky makes it, but Nash is a little slow, the Spinosaurus thrusting its head into the fuselage after him as he runs up the aisle. The weight of the dinosaur's head makes the plane tilt downwards, and Nash, falling, begins to slip down towards its mouth.
He screams for help and grabs at Amanda's legs, but its no use. He slides feet-first right into the Spinosaurus' jaws, which bite down. Nash screams and a single drop of his blood lands on Amanda's cheek. She and the others desperately grab his arms and struggle to pull him free as he pleads for help, but he's yanked from their grasp and right out of the plane.
Outside, the dinosaur swings Nash around in his mouth wildly before dropping him. He lands on the jungle floor, and, still alive, manages to start making a pretty impressive attempt to crawl to safety despite his injured legs only for the dinosaur's foot to come down and pin him. Then the jaws lower and bite down as the others look in horror from the hole in the plane above. Fortunately, Nash's actual death happens offscreen.
The fact the Spinosaurus ate Nash while he had the phone in his pocket allows the surviving characters to hear it coming whenever the phone rings inside its stomach, rather like the crocodile in Peter Pan. And later, when they need the phone, they, rather disgustingly, have to go digging in the dinosaur's droppings to recover it. Amazingly, it survived the Spinosaurus' digestive system completely intact and still usable!
The same can't be said for Nash, of whom only his sunglasses and a leg bone are found.