Driven by the possibility that she put the wrong man behind bars, Olivia discovers that a serial killer has been at large all these years. Believing that the monster has just struck again in Seattle, Olivia leaves her lab and poses as a field agent, sharing her unofficial investigation with a hardworking Seattle cop. Olivia doesn't want to lie to detective Zack Travis. And she certainly doesn't want to fall in love. But as the investigation intensifies, Olivia and Zack find that they're rapidly losing control-over their hearts, their secrets, and a case that threatens to consume them.