For months, members of the McGuire family suffer from chronic illnesses, bronchitis, pneumonia and abdominal pains, fever and chills. When Amy McGuire's respiratory ailments don't respond to any treatment, her parents become alarmed. Amy's mother watches a report on television warning of the dangers of mold in houses. She contacts the local children's hospital, where doctors have seen eight infants suffering from similar ailments, all from living conditions similar to the McGuire's. Investigators inspect the home and discover spores of a toxic mold. The mold, or Stachybotrys atra, lurks and breeds inside walls, behind wallpaper, under carpets or anywhere there may be a water leak.