They arrive in siience and darkness. They descend from the skies. They have a hunger for human flesh. They are everywhe They are parasites, alien creatures who to survive must invade—and take control of—a human host. Once they have infected their victims, they can assume any deadly form they choose—monsters with giant teeth, winged demons, creatur with blades for hands—but most have chosen to conceal thei lethal purpose behind ordinary human faces. So no one knows their secret—except an ordinary