Wikipedia page about this book: https://en.wikipedia.org/wiki/Mathias_Sandorf

Release date is 2007-10-07

Produced by Jeroen Hellingman and the Online Distributed Proofreading Team at https://www.pgdp.net/ for Project Gutenberg

"Mathias Sandorf" by Jules Verne is an adventure novel published in 1885. When a coded message falls into the wrong hands, three Hungarian conspirators plotting against Austrian rule face betrayal and death. Only Count Mathias Sandorf survives, emerging fifteen years later as the mysterious Dr. Antekirtt—a wealthy physician commanding an island fortress. With advanced weaponry and relentless determination, he hunts across the Mediterranean for those who destroyed his friends, becoming a solitary figure devoted to revenge. (This is an automatically generated summary.)

Original publication data not identified