Called back early from a six-month suspension, FBI Agent Gabby Girard is thrust into a case that tests her skills as a profiler. Only one thing is certain-a serial killer is at work. Nothing connects the victims except a black marble chess piece-a knight stuffed in their mouths. What it means eludes her and her new partner, Rachael Goodwin. Just when Gabby thinks she has an accurate profile of the killer, another body is discovered that turns her theory to dust. Bedeviled by false leads and attempts to scuttle her investigation, she homes in on a killer who checks her every move.