Season 1 - Heroic U.S. Army scientist Dr. Nancy Jaax, working with a secret military specialized team, puts her life on the line to head off an Ebola outbreak before it spread to the human population.
Season 2 - With the world still reeling after the attacks on 9/11, America faces a second wave - the anthrax letters. Targeting journalists and politicians, mail with anthrax powder kills five people and causes panic across the United States. FBI Special Agent Matthew Ryker tracks down the hugger, finding himself ensnared in an unstable web of psychological warfare. Bruce Ivins is a brilliant microbiologist who becomes embroiled in the hunt.