Dr. Jeffrey Mann, disillusioned by the South, soured on marriage, returns to Mississippi to investigate a lethal disease outbreak. The disease mosquito-carried encephalitis suddenly emerges in late July in the southeastern corner of the State and health department officials scramble to contain the outbreak. The new form of encephalitis is really strange (having a mixture of characteristics), making genetic engineering or bioterrorism real possibilities. The Centers for Disease Control in Ft. Collins sends the 39 year-old Dr. Mann (specialist in infectious disease outbreaks) to Mississippi to aid local Health Department officials in handling the outbreak. He hates going back because he was deeply offended during adolescence by the rigid, prim and proper South and pressures to conform. During his investigation, Dr. Mann discovers that infectious disease outbreaks are bad enough by themselves, but immensely more serious when intentionally spread.