Coeur de pirate

The body of a man disguised as a pirate is found on the beach. Visibly drowned dead, he is bound feet and fists, would he have suffered the torment of the board? And who is this man, would he be a real pirate? Paul and Leah discover that he had received the famous black mark as in the treasure island, someone threatened him ? Is it related to the treasure of Gaspard Dot that the victim claimed to have discovered ?