Arizona farmer Walter Colby (Woody Strode) and his wife, Birch (Altovise Davis), have a problem on their hands: One of their cows was just killed by a creature, but they have no idea what the beast could have been. So they consult local vet Dr. Robert Hansen (William Shatner), who becomes puzzled and calls in scientist Diane Ashley (Tiffany Bolling). Eventually, the duo discovers that oversize spiders are invading the small town, putting the entire population in danger as a county fair begins.