Ken Wheatley and his team accompanied Claire and the Dinosaur Protection Group to Isla Nublar to round up the dinosaurs and deliver them to another island reserve, since a volcanic eruption is imminent and will kill all the dinosaurs. However, after Owen tracks down the last surviving Velociraptor (known as Blue), Wheatley and his men betray Owen by capturing Blue before leaving Owen, Claire and Franklin to die while keeping Zia to perform surgery on Blue since he needs her alive. As it turns out, Mills plans to capture all the dinosaurs and sell them off as sentient weapons for profit, and that Wheatley is involved with it as he intends to collect a 'significant bonus' for his assistance. To that end, Wheatley and his men managed to capture several more dinosaurs before transporting them into their ship through cages while collecting their teeth as trophies to make as a necklace.
After reaching to the mainland, Wheatley soon learns that Owen and his friends have evacuated. To that end, he gets several of his men to capture them at gunpoint before putting them in a cell per Mills' orders. With the dinosaurs delivered to the auction, the event is disrupted when Owen releases a Stygimoloch to cause havoc, sending several people to flee away from the scene. In the ensuing chaos, Wheatley looks for Mills demanding his bonus before he attempts to go inside the cage of the genetically engineered dinosaur (known as the Indoraptor) to retrieve one of his teeth as a trophy for his necklace, shooting him with two tranquilizer darts to keep him from attacking him. However, Wheatley soon discovers too late that the dinosaur was only pretending to be stunned, allowing the Indoraptor to bite off his arm and gulping it down, leaving Wheatley helpless and at the mercy of the creature. The Indoraptor then proceeds to maul Wheatley to death before escaping from his cage and slaughtering more people (including Gunnar Eversol) along the way.
At first, Wheatley appears to be jovial, polite and even empathetic, as he noticed the sad looks of Owen and Claire and asking them if that was "bad memories". He also tried to prevent Zia from going with them capture Blue, warning her the situation could turn hairy. Later however, his true intentions came to the light and Wheatley is revealed to be a cold and sadistic poacher. His sadism is proven when he heartlessly ripped out a tooth from a conscious Stegosaurus. He is also sarcastic and prone to contemptuous remarks when his true colors are revealed.
Wheatley is greedy, hence why he accepted to have a role in Mills's operation. Because of that, while not outright abusive, he does not care at all about his men and priorizes the capture of the dinosaurs, as seen with Blue when he tells his men to not hurt her even when she wounded a mercenary before. He clearly takes pleasure in his job nevertheless, ripping teeth of dinosaurs to keep them as trophies.
Wheatley is very brave and reckless. This trait is his downfall, as when he shoots the Indoraptor, he does not bother to check if he is really asleep, allowing the latter to attack him. When he is about to die at the mercy of the dinosaur, Wheatley breaks down completely and cries out of fear.
It is hinted he holds contempt towards women, calling Zia a "nasty woman" and threatening to kill her if she doesn't cure Blue.
Ken Wheatly received negative reception. Fans found him to be a laughable and ineffectual character, due to failing to notice the Indoraptor being still conscious, putting his reputation as a hunter into question.
Mills! Mills, where are you? I want my bonus! (sees the Indoraptor in his cage) Holy cow. What are you? I didn't see you on the island.
~ Ken Wheatley seeing the Indoraptor for the first time.
You are a tough guy. Look at that beauty. You're some kind of hot rod. With pretty teeth. This will make a perfect centerpiece for my necklace.
~ Ken Wheatley seemingly sedating the Indoraptor in an attempt to take one of it's teeth.
~ Ken Wheatley's last words before realizing too late that the Indoraptor is toying with him.
Ken with the other mercenaries.
Ken meeting Owen.
"Holy cow. What are you? I didn't see you on the island."
Ken tries to cut off the Indoraptor's tooth, not noticing the latter smiling before killing him.
Ken discovers that the Indoraptor was actually playing possum.
Ken Wheatley is one of the two human villains in the franchise (along with Dieter Stark) to physically mistreat dinosaurs (though the only dinosaurs that Dieter physically mistreated were Compsognathus). However, while both were hate sinks, Dieter respected his fellow hunters' abilities, contrary to Wheatley's complete disregard to anything but himself.
Wheatley is a darker reflection of Roland Tembo, the big game hunter expert hired by InGen during the expedition at Isla Sorna, in The Lost World: Jurassic Park. Both are hunters and they don't drive the main plot in the movies. But Roland was there because of his love of challenge while Wheatley was there only because of his greed. Also, Roland is a calm, wise and moral man who does everything he can to try to keep everyone alive, including two people who explicitly try to have him and his men killed. Wheatley, on the other hand, is a heartless and arrogant man who tries to leave the members of the DPG to die on the island, and doesn't care at all about his own men.
Wheatley is one of the four human villains in the franchise to attempt to kill another human being along with Lewis Dodgson (in the novel), Billy Yoder and Eli Mills. Just like Yoder but unlike Mills and Dodgson, Wheatley failed to kill anyone and while every other villain attempted to do so with their bare hands Wheatley indirectly tried to kill the heroes by leaving them to die on the island.
It was hinted that Wheatley's hunting career may have been a fabrication he made up just to gain notoriety.
The movie heavily implies that Wheatley wanted to betray and sell out Mills after accomplishing his goal as well to avoid getting implicated with him.