While walking her dog on the moorland near the stone circle of Nine Sisters Henge, in the north of England, an old lady discovers the body of a young man, stabbed. The police, who quickly arrived on the scene, soon found the body of a young woman not far from there, killed by a violent blow to the head. Did the victims know each other? Was there a link between them? Is there a reason why the murderer killed them in two different ways?

Thomas Lynley, a friend of the young woman's father, is in charge of the investigation. And the case turns out to be much less simple than the inspector could have imagined. With the help of one of his men, Sergeant Winston Nkata, and Barbara Havers, whom he continues to cold to since his latest misadventures, he will have to unravel the threads of a terribly complex story, with multiple ramifications. It soon turns out that Nicola Maiden, the murdered young woman, was not the wise and brilliant student we thought she was. And that the other victim was hiding very murky activities. All the leads that emerge seem to further confuse the case. Who were the two young people really? Why were they killed? And, above all, who killed them?