A homeless man in Boston, an Army Major in California, and a teenage girl in Atlanta all die suddenly and painfully--each a victim of an unknown doomsday virus. For three days, a team of scientists is a U.S. government laboratory has been frantically trying to unlock the virus's secrets. When the leading researcher from that lab, Lt. Col. Jonathan Smith, returns from overseas, he barely survives a series of well-orchestrated attempts made on his life...