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.

Nikki Alexander finds herself working on a case from her past. Four years previously, she had been instrumental in getting 17 year-old Anna Holland acquitted of a murder charge. She had been accused of egging on her boyfriend in the murder of a young mother they chose randomly. Now, while under police protection, her body has been found in a burnt car. The autopsy reveals that she had been stabbed but had died from carbon monoxide poisoning and so was burnt alive. Nikki also receives a surprise visit from her estranged father who wants her to perform a second autopsy on a friend who recently died.

Nikki Alexander begins to have serious doubts about her conclusions four years previously when her testimony helped acquit 17-year-old Anna Holland of murder. Anna's mother had withheld information from the police and as Nikki reconstructs the scene of the crime, she realizes that the blood spatter evidence no longer holds up. The police focus on the dead woman's husband but the pathologists find that a series of unsolved murders may have a bearing on the case. Nikki is also annoyed with her father, who has conned Harry Cunningham into completing a second autopsy on his late wife.