Udesky is the leader of a crew of mercenaries hired by Paul and Amanda Kirby to locate their missing son, Eric, on Isla Sorna. He outlives his friends Nash and Cooper, but has "expendable meat" written all over him so he ends up suffering a pretty agonizing death at the claws of some Velociraptors.
The group enters an abandoned InGen facility and a chase ensues with a single raptor. Although they manage to make it out of the building, the raptor signals his packmates who soon descend on the humans and begin chasing them. To escape, Alan Grant directs everyone to run through a stampeding dinosaur herd, possibly in the hopes of losing the raptors. It doesn't work and the raptors show no interest in the other dinosaurs, only the humans. Plan B is to make for a nearby jungle.
In the chaos of making it through the herd and running into the jungle, the group is scattered. Grant, who paused to grab Billy's dropped pack, ends up elsewhere hiding behind a log. His assistant Billy Brennan and the Kirbys end up climbing into a tree. Udesky falls down and has to take off his backpack and consequently falls far behind the others. He finds himself alone faced by two of the raptors, who attack him.
We cut away to the characters hiding in the tree, and they hear him screaming. When we cut back to Udesky, he is down on the ground trying to crawl away only for one of the raptors to put a foot on his back and stick its claw into his lower back, making him scream in pain.
It seems he's dead, but a few moments later, Amanda notices him lying on the ground underneath their tree. How the raptors got him there without the humans noticing is unclear. They call down to him, and get no response. "He's dead," Billy says grimly.
Suddenly Udesky begins moving. Paul and Amanda both insist on climbing down to help him despite Billy's warning not to. When Amanda duly climbs down to assist him, she is attacked by the two raptors who come rushing out of hiding and has to be pulled to safety.
"They set a trap!" Billy cries. "They actually set a trap!"
Elsewhere, the hiding Grant is watching two other raptors communicating with the pair who have Udesky, and suddenly one of them seems to take an intense interest in him, signalling to the others to forget about the humans in the tree. They depart, but not before one of them grabs Udesky's head in its jaws and snaps his neck, killing him.
What none of the humans know is that the reason the raptors are after them isn't because they're hungry but because Billy stole some eggs from one of their nests, intending to sell them. They were what was in his pack that he dropped during the stampede, and it was because Grant grabbed it without knowing what was in it that the raptors abandoned their attempt to make the humans in the tree come down and came after him, instead. Having taken the eggs, Billy is the reason the raptors are after them and is more or less the unintentional cause of Udesky's death.
Alone among the death scenes in the film, Udesky's seems like the most mean-spirited on the part of the screenwriter, calling to mind the horrifying fate of Eddie Carr, and the fact Billy is indirectly responsible for his death by taking the eggs is rather maddeningly never brought up by anyone. At least not directly. Also, weirdly, Grant never seems to notice he's missing or ask what happened to him when he reunites with Billy, Paul and Amanda after finding Eric.