It's been four years since the terrifying incidents occurred in Hawaii and Washington D.C., yet Thomas Clark can't stop looking over his shoulder. Now, in late 2001 and in the aftermath of 9/11, he and Laura are challenged with a decision that will define their future. But they're not the only ones facing turmoil. Sam and Bill land on the razor's edge as a judgment call they made, twelve years prior, comes back to haunt them. As the families work together to combat a common enemy they are not prepared for the situation they get placed in, nor do they completely understand what sacrifices they'll have to endure...in Shadows of the Serpent.