The teachers and students of a countryside elementary school are thrown into a panic when an air raid siren goes off, warning them of a imminent nuclear attack. They are unaware that it has gone off by mistake, and separate the children into groups -- one of which is headed by the anxious Mrs. Andrews (Nancy Marchand) -- to take them home. Harriet (Alice Playten) invites her classmates into her family's bomb shelter, but tragedy strikes when she won't allow one of her classmates to enter.