Three and a half years ago, former Grant County medical examiner Sara Linton moved to Atlanta, hoping to leave her tragic past behind. Now working as a doctor at Atlanta's Grady Hospital, she is starting to piece her life together. But when a severely wounded young woman is brought into the emergency room, she finds herself drawn back into a world of violence and terror. The woman has been hit by a car, but naked and brutalized, it's clear that she has been the prey of a twisted mind.

When Special Agent Will Trent of the Criminal Investigation Team returns to the scene of the accident, he stumbles upon a torture chamber buried deep beneath the earth. This hidden house of horror reveals a ghastly truth: Sara's patient is just the first victim of a sick, sadistic killer. Wrestling the case away from the local police chief, Will and his partner Fai.