Detective Mona Lisa Moon is going down. Into her heart of darkness. To find a killer. A killer like her. After killing an unarmed man, Detective Moon is confronted with her cold-blooded alter-ego and the psychological scars of a tragic childhood, and in the midst of hunting down a killer, she becomes what she sets out to find. In Aubrey Shaw, an aging cop biding his time before retirement, Moon meets a man who understands her motivations, and as they solve the case together, their hidden personalities seduce one another, bringing rise to vengeful revelations and a twisted animal attraction.