If the creature in Alien had proliferated like the movie’s knockoffs, mankind would never have survived. This one involves a team of divers exploring a vast cave system, an appropriate setting given the hollowness of the story and acting. Bruce Hunt directed; among the blandly good-looking heroes are Cole Hauser, Eddie Cibrian, Morris Chestnut, and Lena Headey. PG-13, 97 min.