Year 1864. Victor Hugo heads the Republican resistance against the Empire of Napoleon III from his headquarters in exile, the house of Hauteville House. He puts on a mission of espionage Gabriel Valentin-la-Rochelle, known as Gavroche, the best of his agents. The purpose is to ascertain the intentions of a French archaeological expedition, escorted by troops of the Foreign Legion, in a pre-Columbian ruins of Mexico coast. Along with Mexican revolutionaries, Gavroche reaches the site where it has discovered the key to an ancient technology that would give the emperor's military supremacy over British and Prussians.