El Mensaje Llego en una Botella = The Message in a Bottle

Officer Carl Morck is given a bottle that contains a strange message written in human blood. It had been in storage at a precinct in Scotland for years. Carl and his assistants are able to make out a few letters and discover it came from two boys who disappeared in the 1990s. Why didnt their families ever report this? Morck realizes this is not an isolated incident and that the criminal is still out there acting with complete impunity.