Isaku is a nine-year-old boy living in a remote, desperately poor fishing village on the coast of Japan. His people catch barely enough fish to live on, and so must distill salt to sell to neighboring villages. But this industry serves another, more sinister purpose: the fires of the salt cauldrons lure passing ships toward the shore and onto rocky shoals. When a ship runs aground, the villagers slaughter the crew and loot the cargo for rice, wine, and rich delicacies. One day a ship founders on the rocks. But Isaku learns that its cargo is far deadlier than could ever be imagined....