While diving off the coast of Tanzania, spouses Sam and Remy Fargo find a bell with the inscription “Ophelia” on the ocean floor, dotted with Aztec symbols inside. Trying to find out the fate of the ship with that name, they end up in a local museum with very strange exhibits, including a staff with a knob made from the tongue of this very bell. It turns out that the bell previously belonged to a long-forgotten Confederate ship. But what do Aztec writings mean? Intrigued, Fargo continues the investigation, unaware that much more powerful and influential forces are interested in the same case. A group of professional assassins sent by the President of Mexico is pursuing the couple with the goal of killing them and taking possession of the bell, which holds a terrible secret...