She wanted to save lives.

The killer wanted to end hers. 

The first warning was triggered hundreds of miles away. The second warning exploded only yards from where she and her son stood. Now Kate Denby realizes the frightening truth: She is somebody's target. 

Danger has arrived in Kate's backyard with a vengeance. And the gifted scientist is awakening to a nightmare world where a ruthless killer is stalking her...where her innocent son is considered expendable...and where the medical research to which she has devoted her life is the same research that could get her killed. Her only hope of protecting her family and making that medical breakthrough is to elude her enemy until she can face him on her own ground, on her own terms - and destroy him.