When the police are involved in complicated investigations it happens everywhere that they are helped by 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 she has made a living making believe that she can talk to the dead. One evening in August she reads on the news bills that there has been a terrible murder at an institution for young women with destructive behavior. Flora Hansen decides to call the police and claim that she has made contact with the spirit of the dead girl.
The technical investigation without any doubt singles out one of the inmates, a “good", quiet girl, who ran away from the institution on the night of the murder, as the perpetrator. When Joona Linna starts looking into her past, it appears that she has not always been that very good.
Already Joona has spent more time on the scene of the crime than any other detective inspector would. Still he isn’t finished yet, he is thinking that there must be something left for him to see before he can be allowed to leave this gruesome room, he must find a detail that will lead him on, like the needle leads the way of 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. It is difficult to concentrate on this tiny red grain in a room splattered with blood, but he doesn’t give up, he just 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 mazy.
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 desperate, to just listen to her.