The first trailer for Primitive War is here, and it’s a wild mix of military action and dinosaur horror. The movie stars Ryan Kwanten (True Blood) and Jeremy Piven (Entourage) as U.S. soldiers in the Vietnam War who discover something terrifying in the jungle—dinosaurs.

Directed by Australian filmmaker Luke Sparke, Primitive War is based on Ethan Pettus’ book series. The story follows an elite military team called Vulture Squad, sent into a remote jungle in 1968 to find a missing platoon of Green Berets. But instead of just enemy soldiers, they face prehistoric monsters.

“Three days ago, I lost my Green Berets. There was something going on in that battle,” Piven’s character says in the tense trailer. As the squad fights to survive, they realize they must become as savage as the creatures hunting them.

Sparke, who also co-wrote and produced the film, was excited by the crazy concept.