Trieste, the capital of Illyria, consists of two towns of widely dissimilar aspect. One of them—Theresienstadt—is is modern and well-to-do, and squarely built along the shore of the bay from which the land it occupies has been reclaimed; the other is old, and poor, and irregular, straggling from the Corso up the slopes of the Karst, whose summit is crowned by the picturesque citadel.
The harbor is guarded by the mole of San Carlo, with the merchant shipping berthed alongside. On this mole there may at most times be seen—and very often in somewhat disquieting numbers—many a group of those houseless and homeless Bohemians whose clothes might well be destitute of pockets, considering that their owners never had, and to all appearance never will have, the wherewithal to put into them.
To-day, however—it is the 18th of May, 1867—two personages, slightly better dressed than the rest, are noticeable among the crowd. That they have ever suffered from a superabundance of florins or kieutzers is improbable, unless some lucky chance has favored them—and they certainly look as though they would stick at nothing that might induce that chance to come.
Mathias Sandorf is Verne's homage to The Count of Monte Cristo; Verne even dedicated the first edition of the book to Alexandre Dumas. In a sense, it asks the question, "How could a story like The Count of Monte Cristo occur in the nineteenth century?" This necessarily leads to a number of differences, since much of the actual story of The Count of Monte Cristo is tied up in the details of its period; adapting it to a different time requires a great deal of ingenuity and re-thinking. (Mathias Sandorf is also much less about revenge than The Count of Monte Cristo is, but this seems not to have been Verne's original intent. Hetzel, his publisher, was uncomfortable with serializing a revenge story in his family-focused magazine, so Verne had to re-think a number of things in order to make the story more obviously about justice rather than revenge.)
Count Mathias Sandorf is a Hungarian nobleman in the Austro-Hungarian Empire. He and a number of others are involved in a conspiracy to try to liberate Hungary from the Austrians. They fail due to the treachery of some of those involved, which leads to several conspirators captured and executed. Sandorf himself disappears beneath the waves in a hail of bullets. Fifteen years later, a famous physician, Dr. Antekirtt, who is so extraordinarily wealthy that he owns his own private island and a fleet of advanced electric-powered ships, sets out to bring justice to the traitors, who one by one will fall into his grasp.