It's a classic case of "bait and switch." The ranchers at Prosperity Wells are preparing for an invasion of Predators, and are instead set upon by an infestation of Aliens -- that's the "switch." And the "bait". . . ? That'd be the ranchers themselves. Fox's two greatest horror properties, Aliens and Predator, go at it tooth and claw in this very first meeting, presented to an all-new audience as part of the Dark Horse Classics line!
