Part 1 of 2. A CDC doctor (Tiffani Thiessen) looks to contain, identify and treat a rapidly spreading, highly contagious virus that made its way to L.A. on a flight from Australia. Making her task harder are several forces, including uncooperative politicians, quarantined patients who'll do anything to go home, a dangerous prisoner who could be infected and bickering disease-containment specialists. Troy Whitlock: Vincent Spano. Dr. Carl Ratner: French Stewart. Mayor Dellasandro: Eric Roberts.