A team of experts is assembled when the U.S. Navy makes a chilling discovery: An extraterrestrial 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 handpicked 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.