Montana, 1907. Barnum Brown of the American Museum of Natural History aims to dig up fossils of Tyrannosaurus Rex, the most fearsome carnivore ever to walk the Earth. He dismisses rumors of earlier paleontologists encountering both resurrected dinosaurs and aliens from space. He's more worried by reports that notorious bank robber Luther Gumpson is in the neighborhood. But then Brown discovers that the aliens are real, they're back, and they're mad. And he'll see more than the bones of T-Rex, when he encounters the awesome ground-pounding predator in the flesh.