Life is good for Sarah Hoyt. a happy second marriage, a beautiful California home, a blossoming career as a thriller writer. She is even developing an unsuspected talent for marathon running. Until the day nightmare enters her world ...

Someone, faceless, is shadowing the family. A someone who knows far too much about them and their movements. It could be any of their countless visitors. Or, unthinkably, one of the household itself - because the invisible stalker knows the plot of Sarah's latest novel-in-progress, and is transforming it into horrifying reality. As the tension mounts, Sarah finds herself - literally - running for her life.