A miniature painting of a mermaid drawn in bat's blood is taking the art world by storm. Why was it adrift at sea in a bottle, a coded message etched in the glass? Who painted it and why? It is up to Larry Settlebottom, a sheltered museum curator and Pharaoh Williams, his troubled bodyguard with a secret to decipher the riddle, taking them to Mexico and beyond as they encounter modern-day pirates, corrupt oceanographers, and a band of sea gypsies to find the answer.