Lydia is an overweight sales clerk in a trendy home furnishings store, nearing 30. Though she is a member of a Fat Acceptance Group (a movement dedicated to fighting prejudice against overweight people), she is still struggling with complex feelings about her body and its place in the world. Darcy, a recovering-anorexic real estate agent in her mid-20s, is struggling with the same issues from a very different perspective.

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.