The residents of a rural mining town discover that an unfortunate chemical spill has caused hundreds of little spiders to mutate overnight to the size of SUVs. It's then up to mining engineer Chris McCormack and Sheriff Sam Parker to mobilize an eclectic group of townspeople, including the Sheriff's young son, Mike, her daughter, Ashley, and paranoid radio announcer Harlan, into battle against the bloodthirsty eight-legged beasts.

Astronomers discover a comet that they believe will crash into Phoenix, Arizona. They attempt to warn officials, but without 100% certainty, the governor of Arizona is reticent to cause a panic. Even after a television news reporter discovers the truth and threatens to go live with it, the response is understated enough to doom some residents of Phoenix to certain death.

Rancher Cole Hillman is fed up of rabbits plaguing his fields. Zoologist Roy Bennett conducts an experiment to curb their population, but it gives rise to giant rabbits that terrorise the town.