Darkness in a bottle. Adler-Olsen Yu.

The Department of Q Copenhagen is entrusted with an investigation of a very unusual case. The police of Scotland sent the Danish detectives a small bottle thrown by the sea to the deserted shore: a decayed message in the Danish language written in blood was found in it. The text is poorly preserved - time and sea water did their job. Having started the decoding, Detective Karl Mark, along with his assistants, found that in the message a call for help was concluded. What is this children's prank or the last hope of salvation? Karl Mark and his colleagues are trying to use all the possibilities to reveal this and other monstrous crimes of the serial killer, who for many years managed to move away from justice.