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.
In a single instant, her life changes when one of those plans - Threshold - is activated by Deputy National Security Advisor J.T. Baylock. Armed only with her hypothetical strategy to address the appearance of aliens on earth, Caffrey now finds herself thrust in the midst of a global crisis.
She hand-picks a team of eclectic specialists to prepare for first contact: Dr. Nigel Fenway, a disillusioned NASA microbiologist; Lucas Pegg, a brilliant but neurotic physicist; Arthur Ramsey, an expert in languages and mathematics; and Cavennaugh, a highly trained covert operative with a mysterious past.
Together, they decipher the intention of the craft, the fate of the ship's crew and begin preparations for the possibility of a crisis situation-an alien invasion.