A USCMC squad arrives on Ryushi to investigate the disappearance of a colony. They find a crashed Predator ship containing a Queen Alien, and an unconscious Predator. When they try to leave, they are ambushed by Aliens who have buried themselves in the sand outside. The marines fight their way free, but then also find themselves under attack from Predators. They retreat to the colony stockade for a three-way battle with both the Aliens and the Predators. During this, a chestburster emerges from the unconscious Predator - a new, more powerful Alien... a Predalien.