Redemption - Adler-Olsen, Jussi

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... Her husband will not tell the truth: where he goes, how long he will be away.