When a cyber-attack at NASA's Goddard Space Flight Center in Maryland disables the Hubble telescope and the Nobel Prize-winning scientist in charge disappears, the only clues left behind are a cryptic countdown clock and a chilling message displayed on the missing man's computer: Mankind Must Look No Further.
Newly appointed FBI agent Joe Shepherd, a former academic star with degrees in astrophysics and computer science, is uniquely qualified to handle the investigation, but he is also hiding some secrets of his own. He discovers a note in the missing scientist's handwriting that reads "end of days" and further evidence linking the cyber-attack to a series of strange events from eight months earlier—an explosion at the Citadel, an ancient monastery in Turkey; the deadly viral outbreak that occurred in its wake; and the disappearance of an American journalist named Liv Adamsen and ex–special forces operative Gabriel Mann.
Liv has been trapped in the Syrian Desert, a prisoner of the prophecy that drove her there and now whispers of terrible things to come. Gabriel, infected and tormented by the deadly virus he carried out of the Citadel, is desperate to return before it spreads.