Sound of Thunder

In a future where people travel through time for recreational purposes, a popular sport is going back to prehistoric times to hunt prehistoric wildlife. These prehistoric safaris have only one rule, to kill only those animals that are meant to die. A careless tourist accidentally kills a prehistoric butterfly and it sends off a wave of cataclysmic time changes that result in the extinction of man from the planet. Now, a small group must find the deceased butterfly and return him to an earlier time-and life, hopefully saving mankind as a result.