Why has Eckels come to the Time Safari office? What does he plan to do?

It’s the year 2055. Eckels is a hunter. He’s come to the Time Safari office in order to be taken back to prehistoric times and to kill a dinosaur. He’s paying $10,000 for the opportunity to do so. At least, this is his plan. He joins a hunting party led by two guides, Travis and Lesperance; and they use a time machine to go back to the crucial moment. They’re going to kill a Tyrannosaurus rex that would have been killed by a falling tree anyway. But once faced with the tremendous beast, Eckels becomes terrified. He stumbles back to the time machine, not even realizing that he has stepped off the Path that everyone was warned to stay on. The Time Safari people had done their best to make sure that their actions would not impact the future in any way. Of course, once they return to 2055, they see that this is not the case. Eckels’ misstep has evidently set off a series of changes that now make contemporary life quite different than it was before.