Worlds collide when a T-Rex-riding alien from a prehistoric planet travels to Earth to close a portal between his world and ours and stop an all-out war with a tribe of fearsome, Raptor-riding warriors.

Dos Locos, Texas: a two-bit, backwater cattle town locked in the grip of one Dante D’Allesandro. D’Allesandro has made a fortune in ranching but as the 1800s draw to a close, unless something dramatic happens, D’Allesandro realizes the sun is about to set on the cowboy way of life. And then – seemingly out of nowhere – a full grown bull Triceratops wanders into town and nearly destroys it. D’Allesandro sees the opportunity he’s been searching for.

Zeke Calhoun is a 14-year-old struggling to fit in on his Uncle Jesse’s broken-down ranch on the outskirts of town. He has a crush on D’Allesandro’s niece, Angelina, and she seems to like him, too. Too bad Uncle Jesse acts like he has a rock stuck in his boot 24/7 and the two don’t get along. All that changes when Zeke discovers a mysterious eight-foot-tall stranger riddled with bullets and a juvenile T-Rex the size of a horse protecting his owner from a pack of hungry wolves. Where did the stranger come from? Who shot him? And why?

Zeke rescues the stranger and hears a story that sounds too outlandish to be true: D’Allesandro is planning to rustle a herd of Triceratops from the stranger’s world and bring them back to Texas! And unless he’s stopped, Dos Locos will be leveled by a tribe of vengeful warriors. With time running out, Zeke, Angelina and Uncle Jesse must join forces with the alien stranger known as the “Rex Rider” and stop D’Allesandro before it’s too late!