On a crisp September morning, a jogger stumbles upon a horrific scene in a London park...

When forensic photographer Kate Gardener steps in for her injured supervisor, the brash young American finds herself at the scene of a brutal murder. The body of university student Daniel Norton has been found at the edge of Regent's Park – naked and castrated. Gifted with a "photographic" memory, Kate is uniquely suited to capturing the details of a murder scene, and reading the shadows and light of her crime scene photos. But this crime scene is different...

As the investigation proceeds, the victim is linked to a decade-old crime, the murder of Helen Flynn. Then, a second body is discovered, the crime scene more brutal than the first. After crime scene photos go missing – and a coworker's strange behavior takes center stage – Kate fears that the murderer may be very close... and about to strike again.

Kate's instincts for solving crimes have always been spot-on... could this killer really be one of their own?