When dealing with a complicated investigation, the police sometimes turn to a spiritualistic medium. Still there is no evidence of one single incident where a medium has contributed to the solving of the case.
Flora Hansen calls herself a spiritualistic medium, and for many years has made a living pretending she can talk to the dead. One evening in August, she reads in the news about a terrible murder at an institution for young women with destructive behavior, and decides to call the police, claiming to have made contact with the spirit of the dead girl.
The official investigation singles out one of the inmates, a quiet "good" girl who ran away from the institution on the night of the murder, as the possible perpetrator. When Joona Linna starts looking into her past, he learns that she hasn't always been that good.
Joona has already spent more time on the crime scene than any other inspector would, but he isn't finished yet, thinking there must be something left to see before he leaves the gruesome room - some detail that will lead him on, as a needle leads the thread. He looks at the girl on the bed; her naked skin still radiates a faint warmth. Her hands are shut over her face, as if she is playing hide and seek. He cautiously bends over her and discovers that something is stuck under the nail of her left index finger. It looks like a dark red grain of sand, like a splinter from a ruby.
He blinks and tries to make his eyes focus sharply on the tiny red grain in a room splattered with blood. He bends closer; he feels the sweet smell coming from her, and suddenly he realizes what it is that he sees under the nail.
Over and over again the hunt for the murderer takes violent and unexpected turns. Each new answer only appears to lead to new riddles, and what seemed so simple a moment ago is suddenly hazy.
But even when the investigation has reached a deadlock, the police ignore Flora Hansen's phone calls. First she asks for money for the information she can offer, but later she begs them, more and more desperately, to just listen to her.
