In the Jurassic Park novel John Arnold was Jurassic Park's chief engineer. He was described as a thin, chain-smoking man and a chronic worrier. Before working at Jurassic Park, he worked as an aerospace engineer for the United States military, developing missiles. However, after the birth of his first child, weapons seemed too deadly and distasteful a career for his family. He then moved into developing and engineering theme parks; including Walt Disney World in Orlando, AstroWorld in Houston, and several other zoos and parks. He was depicted as somewhat of a peacemaker, as he restrained Hammond when he tried to pick a fight with Nedry about the bugs in the park's system. Arnold was fairly certain that Jurassic Park would work out in the end and stated several times that he disagreed with Malcolm's predictions on the collapse of the park. He diligently worked on getting Jurassic Park back online with the help of Henry Wu throughout the novel.
Donald Gennaro eventually convinced Arnold to shut down the system. When the system came back online it was running on backup power. Arnold and the rest of the InGen staff were unaware of this until an 'AUX POWER LOW' warning popped up on Arnold's computer. This led Arnold to realize that the electric fences were not being [[File:Jpark.jpg|thumb]] powered and had been kept off for a significant amount of time. This caused great distress among those in the control room, especially Robert Muldoon, the park's game warden. Muldoon and Arnold set off together to the maintenance shed to restore the park's systems, but were separated when Muldoon was attacked by a group of raptors. Arnold made it to the shed but was horrified to realize that a raptor had come in after him. He believed that he was safe when he descended a staircase that the raptor could not climb down. Arnold looked back at the ''Velociraptor'' and said his last words, "Too bad, buddy," right before the raptor leaped down the stairs and pinned him to the ground where his fear overcame him, not allowing him to injure the raptor, ward off the raptor, or even scream.
Ray Arnold is the chief engineer of Jurassic Park. His catchphrase was "Hold on to your butts," which he repeated twice in the film. Arnold was usually shown smoking a cigarette. In the first edition of the script, Hammond was greatly concerned for Arnold's health due to his constant smoking. He made frequent announcements over the loudspeaker informing the other employees on the position of the approaching storm. After Dennis Nedry turned the power off he told John Hammond that he couldn't get Jurassic Park back online without Nedry. Arnold showed great irritation with Nedry's personal touches to the park's system.
Sometime Sunday morning, Hammond told Arnold to shut down the entire system and restart it. Arnold was against this idea because they had never shut down the entire system before and he was not sure that it would come back on at all. Despite this, Hammond was adamant and Arnold eventually shut down the system. He was greatly relieved, along with the rest of the survivors in the control room, when the computers came back on. He set off on his own to the maintenance shed to re-boot Jurassic Park while the rest of the survivors went to the security bunker to await his return.
After a few minutes went by with still no sign of Arnold, Ellie Sattler realized something must have gone wrong and set out to re-boot Jurassic Park with the help of game keeper Robert Muldoon. However, the two found themselves stalked by the Velociraptor pack, and Muldoon told Ellie to head to the maintenance shed by herself while he deals with the raptors.
While restoring power to the shed, Ellie was ambushed by a raptor, and while trying to escape she stumbled across Ray's severed arm, revealing that he had been killed by the raptor whilst trying to reboot the park.
After the incident in Jurassic Park, Arnold's family sued InGen in a $23 million lawsuit.