德克萨斯的一座小城在进行一项民意调查,这时发生了一系列令人不可思议的事件,蝙蝠袭击了当地居民!政府部门指派野生动物学家希拉.卡斯珀去调查此事。蝙蝠通常是一种无攻击性而且性情十分温和的小动物,可在这里,每当太阳下山,成群的蝙蝠变得十分恶残,一时间,举行民意调查的场所竟然变成了令人毛骨悚然的危险之地。 希拉与小城的治安长官埃米特.金赛合作,他们探寻这些只在夜间出没的哺乳动物为何会突然改变习性,但是袭击事件仍然频频发生,希拉和金赛必须在一场谋杀实施之前查出并捣毁蝙蝠的巢穴。Bats, the result of a government experiment gone wrong, have suddenly become intelligent, vicious, and omnivorous, and are attacking people near Gallup, Texas. Bat specialist Sheila Casper and her assistant Jimmy are brought in but can they stop the bats before the military comes in and, in their ignorance, makes things worse?