Two boys, brothers, wake tied and bound in a boathouse by the sea. Their kidnapper has gone, but soon he will return. Their bonds are inescapable. But there is a bottle and tar to seal it. Paper and a splinter for writing; blood for ink. A message begging for help.

In Copenhagen's cold cases division Carl M?rck has received a bottle. It holds an old and decayed message, written in blood. It is a cry for help from two boys. Is it real? Who are they and why weren't they reported missing? Can they possibly still be alive?