In the short story, Bradbury posits that when time travel becomes possible, there will be a lucrative business to be made sending people to the Cretaceous Period, where they can hunt dinosaurs. There are strict rules: The dinosaur must be one that's just about to die anyway, and all time travelers must stay on a suspended path so as not to disrupt the ecosystem. Changing one thing, however minor, can cause a ripple effect that might drastically alter the future. Needless to say, a rule is broken, and our heroes return to their time to find it a fascist dictatorship.
The movie begins the same way. Ben Kingsley, sporting a wig that makes him look like Bill Maher, plays entrepreneur Charles Hatton, CEO of Time Safari. Edward Burns is Travis Ryer, a hunky biologist who also happens to be an expert marksman, hired by Hatton to supervise the time trips. Ryer is on board because he hopes the trips will eventually provide DNA scans of extinct animals that would allow for them to be recreated in the present -- a plague has wiped out all wildlife in his time and corrupted the available samples.
Hatton's supercomputer, which has a female voice and is named T.A.M.I., has pinpointed the soon-to-be resting place of an allosaurus about to be trapped in tar and then covered in molten lava. This is the dinosaur that Ryer takes customers back in time to shoot, over and over again. It's a terrible-looking dinosaur, rendered in poor-quality computerized animation that's simply unacceptable in a post-Jurassic Park feature, or even an Xbox game. But here it is anyway.
Once again, something goes wrong, but instead of creating a dictatorship, the alteration to the timestream just causes some mighty big plants to grow and global warming to accelerate. That's the initial effect, anyway. After that, large computer-generated ripples wash over everything at intervals that are sometimes predictable, sometimes not. Each ripple creates an evolutionary change in a higher level of species than before. So after plants it's bugs, then lizards . . . and the final one will be humans.
So it's up to Ryer to work alongside former foe Sonia Rand (Catherine McCormack) -- the scientist who invented T.A.M.I. and knew that something like this would happen -- to figure out what went wrong and fix the past before they change into monsters. If you've read the short story, you already know what went wrong. If you haven't, the marketing geniuses behind the movie give it away right up front on the poster. Either way, you have a massive head start on the characters.
What's truly amazing about A Sound of Thunder is how utterly unaware everyone seems to be that the whole thing is both shoddy and ridiculous. The technology used by Ryer and his colleagues looks as if it came out of Adam West's Batcave, and the notion of giving a talking computer a silly name like T.A.M.I. was ridiculed to death in Team America. The special effects are crap, and we even get the token black guy who gets mortally injured and gives the hero a speech about how he has to go on. Ryer watches at a safe distance while his darker-skinned pal gets eaten by monsters, and only then does he proceed. What a dick.
If you can get past all that, the lousy science (this movie is to Darwin what Megiddo: The Omega Code 2 was to Christianity), and the hilariously banal dialogue ("Everything's going really weird!"), it is possible to roll with things a bit -- it's like watching a video game in which new creatures show up every level to fight you in new ways. The allosaurus may have been ugly and fake, but the raptors with baboon heads just might grow on you. As a TV movie, this would all be quite watchable. In the theater, it's a waste.
Incidentally, the film is being released by Elie Samaha's Franchise Pictures, which boasts an all-star lineup of cinematic disasters: Driven, Heist, The Art of War, The Whole Ten Yards, Angel Eyes, and Battlefield Earth. Among the writers are the people who brought you Sahara, See Spot Run, and Gossip. If you choose to go see it anyway, you are beyond any help available here.