Sam is shaken when she has to look into the death of a very dear friend, Dr. Annabelle Evans, a Cambridge professor. She was found in her home, badly beaten in what appears to be a botched burglary attempt. The police immediately focus on the husband as the likely killer but Sam suspects that an altercation at a local restaurant during the May Ball, where a waiter spilled wine on Annabelle and was fired on the spot, may provide another suspect. Sam is also intrigued by the relationship some of her students may have had with Annabelle, particularly when she learns her friend may have had a lover. In her personal life, Sam has moved on. Her sister Wyn has relocated to Ireland and Peter Ross has also been transferred. She does however run into an old friend who also happens to be an acquaintance of her business partner Trevor.

As Sam, et al continue to look into Annabelle's violent murder, another woman is similarly assaulted.

Harry investiga la muerte de una mujer que se ahogó en una piscina del patio trasero. Aparentemente, fue golpeada en el costado de la cabeza y su esposo afirma que le falta su collar caro. Leo y Nikki investigan la muerte de Lucie Philips, una víctima de secuestro que fue llevada una semana antes. El padre de la niña intentó pagar el rescate, pero el dinero nunca se recogió, lo que lleva a la policía a creer que los secuestradores podrían tener otros motivos. También investigan el asesinato de un repartidor de pizzas que tiene similitudes con la escena del crimen de Philips. Un tercer asesinato lleva a la policía a sospechar que podrían estar presenciando el trabajo de un asesino en serie. La abuela de Nikki muere, lo que la pone en contacto con su padre distanciado.

Leo y Nikki encuentran otra víctima que aparentemente fue atada y enterrada viva. Sin embargo, continúan teniendo dificultades para encontrar un vínculo común entre todas las víctimas. La investigación se centra en el editor de una revista filosófica que tuvo un desacuerdo intelectual con una de las víctimas, pero el caso es más complejo de lo que se imaginaban al principio. Harry descubre que su víctima que murió ahogada estaba embarazada, lo que pudo haber contribuido indirectamente a su muerte. El padre de Nikki es liberado de prisión y desaparece rápidamente.

Harry and Nikki deal with the case of a young woman who is found dead in an animal shelter. Her dead body has obviously been posed and the autopsy reveals she may have been tortured before death. Information from police intelligence suggests that they may be dealing with a group of radical animal rights activists. It all becomes quite personal for Harry when Nikki is taken prisoner. It's also a difficult time for Leo who has been asked to appear before a medical council hearing and testify on the propriety of a close friend's medical research. Harry has been offered a prestigious chair at an American university, but has had difficulty discussing the issue with his colleagues, especially Nikki.

Harry and the police desperately search for Nikki as they continue to find more bodies. The animal rights activists' target is a well known pharmaceutical firm that is undertaking research on behalf of the government. Leo finally decides on a course of action in testifying at the medical council hearing.