A team of experts are assembled when the U.S. Navy makes a chilling discovery: an extra-terrestrial craft has landed in the mid-Atlantic Ocean. Dr. Molly Anne Caffrey is a government contingency analyst whose job is to devise response plans for worst-case scenarios. When her plan (called THRESHOLD) is activated upon the news of the UFO, she and her hand-picked team of eclectic specialists get to work deciphering the intention of the craft and preparing for the possibility of a crisis situation -- an alien invasion.