When forensic pathologist Lucy Trask stumbles across a mutilated body in her local Baltimore park, its face unrecognisable, her sole concern is that it might be her old school teacher. On identification Lucy is shocked to discover that the victim is actually another man from her past. Who killed him and why was he left for Lucy to find is unclear but what appears to be a number 1 burned into his back proclaims that this corpse won’t be the last. The discovery of a second body raises worrying questions: how many more lives may be at risk before the killer’s real intent is revealed? And can Lucy solve the killer’s gruesome puzzle before his thirst for revenge is complete?