When a boat carrying illegal passengers is found crashed in the Thames, the team investigate.

The team follows the trail of the people traffickers, and has to find any remaining survivors before a highly contagious disease breaks.

Harry investigates a case of hit and run where the victim was a 16 year old boy from the nearby housing estate. Working with Sgt. Susan Fenn, they attempt learn if this was an accident or intentional. Harry takes quite a liking to Susan and is shocked by a sudden turn of event. Leo examines a death resulting from a house fire where the lady of the house died. He is puzzled at why she was unable to leave and the police immediately suspect the husband, who was in a nearby park with the children, of murder. Nikki looks into the case of a young woman who collapses at her hen night. She had recently had minor surgery and was taking pain killers, but there is surprising information to be found about her background.

The pathologists busy week continues with a variety of cases. Nikki examines a death in a telemarketing office. Several workers were vying for promotion and the police suspect foul play. Harry deals with the case of a professional footballer who committed suicide. He realizes there is a link to another case he is working on. Leo deals with the case of a drunk who died on a bus. There is little information about the man and the case becomes more of a puzzle when the autopsy reveals that he wasn't drunk at all.

Harry está impactado cuando su antigua novia universitaria, Penny Harris, aparece muerta. Ella estrelló su coche contra un árbol y la policía inicialmente sospecha de suicidio, pero la autopsia revela que la medicación en su sistema estaba triturada en lugar de estar en forma de pastilla, por lo que concluyen que probablemente fue asesinada. Su esposo le dice a la policía que pensaba que su esposa estaba teniendo una aventura y sus padres reaccionan de manera extraña ante la noticia. Leo ayuda a la policía en la muerte de Jimmy Triangle, un artista conceptual cuya última obra trató sobre la muerte del arte conceptual, e incluye su propio cuerpo, ya que le dispararon en la cabeza. La pregunta es si el disparo fue autoinfligido o no.

Nikki y Harry continúan investigando la muerte de Penny Harris. Harry se sorprende al enterarse de que aparentemente en algún momento de su vida había tenido un hijo, pero su esposo niega tener conocimiento de ello. Otra muerte en la familia Harris les permite acotar los sospechosos e identificar al asesino. Leo sigue buscando pistas y la policía cree haber resuelto el caso a través de pruebas de huellas dactilares, pero Leo logra demostrar que el sospechoso ha sido incriminado. La afición de las víctimas por grabar en video sus actividades proporciona una pista vital.

Alison Garland is a 14 year old schoolgirl found dead on the school grounds just after lunch. She appears to have slit her wrists and committed suicide, but there is also evidence that she had sexual relations just earlier that day. As Leo Dalton looks into the case he learns that Alison was also a school bully and was a very unhappy young woman. Harry assists the police in the stabbing death of a car dealer. The evidence suggests that he was stabbed in his garage and his body then dumped. The case takes a radical twist when they find that the knife found by Alison's body was also used to kill the car dealer. Nikki assists the police in the death of an elderly woman who appears to have been maltreated.

A third murder is discovered on school grounds and Leo realises the killings are connected to a sinister teenage pact. Meanwhile, Nikki proves her elderly victim died of hypothermia - but there is still a guilty party to be caught.

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.