A young man and his sister are face to face with starvation, when they receive a letter signed "Thomas Wood, the Red Privateer," who confesses that he killed their father, Daniel Hardy, and sold his ship. Stricken with remorse, he bequeaths his treasure, buried in the Island of Loos, to them. The brother and sister consult a solicitor, who advances them money for the journey. But the captain of the ship in which they travel discovers their secret, and informs the crew with the exception of one man, who, however, hears the captain talking to the others, and warns the brother and sister. When the time comes to land, young Hardy manages to leave the captain behind with some of the sailors. The captain follows, and a struggle ensues, during which he is killed and his accomplices are made prisoners. The Hardys are successful in finding the treasure, and they sail away from the island with the sailors bound fast to the mast.