Bradbury initially creates suspense when one of the Time Safari officials tells Eckels that their company does not guarantee his safety during the expedition. Eckels's expedition to the distant past, where he will hunt a prehistoric Tyrannosaurus Rex, is suspenseful and provides an element of danger to the plot. Travis, the Safari Leader, adds to the suspense by informing Eckels that six Safari Leaders and a dozen hunters were killed last year. The reader senses that Eckels is risking his life for the chance to hunt a deadly Tyrannosaurus Rex.
Once the hunters and Safari guides travel back in time, Travis proceeds to lecture everyone on the importance of staying on the path and obeying every directive. His emphasis on obeying the rules and not altering the environment increases the suspense and foreshadows Eckels's tragic mistake. The tension continues to rise as Travis elaborates on how one mistake can dramatically alter human history, which makes Eckels's expedition even more daring and uncertain. Bradbury continues to increase the suspense when the hunters hear the sound of thunder, which is actually the sound of the Tyrannosaurus Rex stomping through the forest. Bradbury's description of the horrific, massive dinosaur and Eckels's impulsive reaction intensifies the mood of the story as the reader wonders if Eckels ran off the path.
The suspense continues to rise once Travis discovers that Eckels did not remain on the path and could have possibly altered the future indefinitely. Knowing that Eckels left the path, the reader is excited and nervous to discover if Eckel's accidentally altered human history when they travel back to the present in the Time Machine.