Dan Floyd, a retired and widowed lawyer, is doing his best to fill his time - attending church, keeping in touch with his two adult sons, and reading up on epidemics. When he comes down with what seems like garden-variety flu, he amuses himself by studying plagues, both modern-day varieties and the biblical kind. Dan and his sons, one of whom is a doctor, share information and speculate about epidemics. Meanwhile, in the community around him, he begins to hear of people dying from complications brought on by the flu - many of whom attend his church. Dan soon finds himself investigating...