The marriage between Lindsay O'Neil, head of a women's shelter, and Detective Zack Kier has been on the skids for a while. But when what soon becomes a string of serial murders zeroes in on Lindsay, they become up close and personal once again.

Zack has never forgotten Lindsay. Their lives may have drifted apart, but she still holds more than a place in his heart.  When a severed hand turns up in her yard, a gift from "The Guardian," the name for their serial killer, he is scared out of his mind, not sure if the killer is someone who wants Lindsay dead or if he insanely believes he is helping her

At the shelter, Zack wants Lindsay under lock and key with him as the jailer. 

Lindsay's love for Zack has never diminished.  Expecting divorce papers, she is surprised that he's never filed.  When the killer gets closer to her and his gifts are coming more regularly, she is terrified but not sure if she can handle being too close to Zack.  All that changes when Lindsay is kidnapped.  Before Zack can get to her, "The Guardian," shows up...  to protect or to kill Lindsay is the question on all their minds in I'm Watching You.