The four kids find that Mr. Benedict planned a treasure hunt but he is not there because he was captured by his evil twin, Mr. Curtain in which he threatens all of them if they don't find a rare plant that he needs.They figure out a clue leading them to sneak out to a ship called the MV SHORTCUT which the fastest ship in the world. This takes them to a castle in Belguim finding the next clue in a barrel. The riddle unscrambled to going to a train station leading them to a library in Thernbaakagen.