Eckels, a wealthy man, visited Time Safari Inc., a company that offered time-traveling safaris to hunt dinosaurs. He paid ten thousand dollars to hunt a Tyrannosaurus Rex. The company's officials warned him not to deviate from the designated path and not to shoot any animal without their permission. They explained that even the smallest change in the past could have catastrophic consequences in the future.
The group, consisting of Eckels, Travis, the Safari Leader, his assistant Lesperance, and two other hunters, Billings and Kramer, traveled back in time to 60 million years ago.
They were equipped with oxygen helmets and sterilized clothing to avoid contaminating the past. Lesperance had already marked the dinosaur they were supposed to kill with red paint. This particular dinosaur was chosen because it was about to die naturally, ensuring that their actions would not disrupt the balance of nature.
Upon encountering the Tyrannosaurus Rex, Eckels became terrified and ran off the designated path, despite the warnings.
"It can't be killed," Eckels pronounced this verdict quietly, as if there could be no argument. He had weighed the evidence and this was his considered opinion.
The group managed to kill the dinosaur, but Travis was furious with Eckels for disobeying the rules. He forced Eckels to remove the bullets from the dinosaur's body, as they could not leave any trace of their presence in the past.
When they returned to the present, they noticed subtle changes in their surroundings. The sign at Time Safari Inc. was now spelled differently, and Eckels asked who had won the recent presidential election. He was shocked to learn that Deutscher, a dictator-like figure, had won instead of Keith, the candidate he had supported. Eckels realized that his actions in the past had altered the course of history.
Distraught, Eckels begged to go back in time and fix his mistake, but it was too late.
"Not a little thing like that! Not a butterfly!" cried Eckels.
Travis, enraged by Eckels' actions and the potential consequences for their business and the world, raised his rifle and shot him.