When Kate Marshall finds the bloated body of a young man floating in the Shadow Sands reservoir, the authorities label it a tragic accident. But the details don't add up: why was the victim there, in the middle of the night? If he was such a strong swimmer, how did he drown? Kate is certain there is more to this case than meets the eye. As she and her research assistant Tristan Harper dig deeper, they discover a bloody trail that points towards an active serial killer hiding in plain sight. People have been silently disappearing for years, and when another woman is taken, Kate and Tristan have a matter of days to save her from meeting the same fate.