Redemption by Jussi AdlerOlsen

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. Paperback softback