Kay Adler is a hardworking Chicago detective who seeks justice for the victims of murder. She has one close friend, no lovers, and a difficult family. Her life is her work. If she drinks enough on her off hours, it suits her just fine.

When people she knows start dying, her team works to track down the killer. He's a master of disguise and impossible to find, and she must look at uncomfortable parts of her past to find a suspect. She finds two. She's removed from the case because of her personal involvement and is replaced by Detective Jamie Sidwell, a woman with whom she has a troubled relationship. Their uneasy alliance takes them places they never would have guessed, but their bond is tested when the killer turns his sights on Kay.