New series. Part one of two. Nikki struggles to come to terms with life back home and seeks out fellow pathologist Sally Vaughan for support, only to learn she is nowhere to be found. National Crime Agency investigator Guy Bernhardt asks Nikki to help him by employing pathologist David Cannon, the chief suspect in Sally's disappearance. As Jack, Clarissa and Thomas share concerns about Nikki's wellbeing, a body found in a reservoir is linked to a murder case from 16 years previously. Return of the crime drama, starring Emilia Fox, with Julian Rhind-Tutt and Alex Macqueen.