A man pays 10,000 dollars to take a visit to the past. Not just a few years into the past, but to the jurassic ages. He talks with an attendant at the desk, and the attendant tells him that they guarente nothing, so he isn't sure if he will be safe.
This is a lot of money... It better be worth it!
They travel to the past, and the instructor explains that they mustn't step off of the path, no matter what. A small step could influence the entire history of the world. Eckels is still very excited about hunting these ancient beasts.
They arrive in the past, and the group is reminded again by the leader, Travis, that they mustn't step off the path. Eckels is terrified by the dinosaur, and he begins to have second thoughts. They continue down the path, and encounter the dinosaur. Eckels describes this as "the sound of thunder"
Dazed from his terror, Eckles steps off the path. Gunshots rain all around him as the rest of the travelers frantically try to kill the beast.
Somehow Eckles finds his way back to the time machine. When he gets there, Travis is very upset. He decided that Eckels can't return to the present, and he must die. After a while, Travis lets up, and says that he can return if he takes all of the bullets out of the monsters skull.
They return to the present, but as they get their, they notice something different. The air smells just a little different, and the receptionist at the desk is the same guy, but not. The president that was recently elected when they had left was no longer president. By taking a few steps, he had changed the entire course of history.
As Travis and Eckels begin to realize that history was changed, Travis kills Eckels. He hears the sound of thunder again as he is shot.