A hunter named Eckels pays $10,000 to join a hunting party that will travel back 65 million years to the Late Cretaceous period, on a guided safari to kill a Tyrannosaurus rex.
As the party waits to depart, they discuss the recent presidential elections in which a candidate, Deutscher, has been defeated by his opponent Keith, to the relief of many concerned.
Travis explains that the hunters are obliged to stay on a levitating path to avoid disrupting the environment, any deviation will be punished with hefty fines and prosecution, Time Safari scouts had been sent back to select and tag prey whose death will have minimal effect on the future prior to the hunt, and the time machine "steps aside" to prevent people from encountering themselves in the past.
Upon returning to 2055, Eckels and the rest of the party notice major changes; English words are now spelled phonetically, and worst of all, Deutscher has won the election to the approval of the pro-fascist populace.
Looking at the mud on his boots, Eckels finds a crushed golden butterfly, whose death has apparently changed the nature of the alternative present to which the safari has returned.