Two young brothers wake tied up and gagged in a boathouse by the sea. Their bonds are inescapable. But, just perhaps, there is a way to cry for help . . .
Years later, in Copenhagen's cold cases division, Detective Inspector Carl Mørck receives a bottle. It holds an old and decayed message, scratched in blood, from two boys. Is it real? Who are they and why weren't they reported missing? Can they possibly still be alive?
Though the investigation initially appears hopeless, soon Carl and his team find themselves on the trail of not just these missing children - but others. Boys and girls taken - never to be seen again.
And a cold-hearted killer unable to stop . . .