At the Center for Disease Control, epidemiologist Dr. Kayla Martin and her partner Carl Ratner receive a frantic call from a flight attendant high above the Pacific. A nineteen-year-old male passenger, en route to Los Angeles from Australia, has died following a raging fever and violent convulsions. Vehemently concerned about the symptoms, Kayla orders all passengers quarantined upon their arrival at LAX—a decision at odds with Mayor Richard Delasandro who suggests the only outbreak will be one of panic. The CDC considers the frightening possibilities—the reality of the bird flu, the probability of a biological attack, or worse, a new virus they can't control.