It's twenty years after the events of the first movie and the "Park" is now a successful dinosaur filled amusement park. Two brothers, one a teen and the other a t'ween, are sent there for a week to visit their Aunt Claire (Bryce Dallas Howard), who is in charge of the place. She has little time so they are handed off to her assistant. Then there's Owen, an ex-Navy seal who has been training Raptors to obey his commands. Of course, there's a "thing" between Claire and Owen, which gets worked out by the end.
In order to get more visitors to the island the scientists have created a hybrid creature. It escapes and begins killing all the other dinosaurs--and is heading towards the populated area of the park. It's up to Owen and his raptors to try to stop the creature.
This was a good movie. It's not great--and I think I actually enjoyed PART III much better--primarily because it's nearly a remake of that very first film with all the similar plot points. However, I did dig the new dinosaur, Indominus Rex, a creepy cross between a T-Rex and a Veloceraptor. The big battle at the end between the dinosaurs is worth watching the movie for.