Harry investigates the death of a woman who drowned in a backyard pool. She was apparently struck on the side of the head and her husband claims that her expensive necklace is missing. Leo and Nikki investigate the death of Lucie Philips, a kidnap victim who was taken a week previously. The girl's father tried to pay the ransom but the money was never collected leading the police to believe that the kidnappers may have had other motives. They also investigate the murder of a pizza deliveryman that has similarities with the Philips crime scene. A third murder leads the police to suspect that they may be seeing the work of a serial killer. Nikki's grandmother dies bringing her into contact with her estranged father.

Leo and Nikki find yet another victim who was apparently bound and buried alive. However, they continue to have difficulty finding a common link among all of the victims. The investigation focuses on the editor of a philosophical journal who had an intellectual disagreement with one of the victims but the case is more complex than first imagined. Harry discovers that his drowning victim was pregnant which may have indirectly contributed to her death. Nikki's father is released from prison and promptly disappears.

Harry is shocked when his former university girlfriend, Penny Harris, is brought in dead. She drove her car into a tree and the police initially suspect suicide but the autopsy reveals that the medication in her system was ground rather than in pill form, so they conclude she was likely murdered. Her husband tells the police that he thought his wife was having an affair and her parents react strangely to the news. Leo assists the police in the death of Jimmy Triangle, a conceptual artist whose latest work dealt with the death of conceptual art - and includes his own body, as he is shot through the head. The question is whether the shot was self-inflicted or not.

Nikki and Harry continue to investigate the death of Penny Harris. Harry is shocked to learn that she had apparently at some point in her life had a child but her husband denies any knowledge of such. Another death in the Harris family allows them to narrow the suspects and identify the killer. Leo continues to look for clues and the police think they have solved the case through fingerprint evidence, but Leo is able to prove that the suspect has been framed. The victims penchant for videotaping his activities provides a vital clue.