For five years, two murders have lain unsolved and nearly forgotten in the police vault in the quiet little burg of Frederick, Maryland. Until a young lawyer turns up dead, and the familiar pattern of the Coworker killer plunges the sleepy northern town back into darkness. As the body count begins to rise, it soon becomes chillingly obvious that this time the killer has no intention of stopping. Lacking a suspect, hounded for answers by the ravening media, the police have nowhere to turn but Nate Castle, College teacher by day, locally-renowned PI by night. The case of the faceless Coworker murders is the most demanding of his career. Nate is thrust into a spotlight he's been avoiding for the past decade. Somewhere out there is a predator against which Nate is the only defense, but the troubled detective has his own demons to fight. Haunted by regret, crippled by the bottle, Nate stands alone in the darkness, challenging a foe he cannot see. Then the Coworker makes a small but critical mistake. And that's when-all hell breaks loose.