"The King of the Mountains" by Edmond About is a French novel published in 1857. A German botanist searching for rare plants in Greece is kidnapped alongside a wealthy English mother and daughter by Hadgi-Stavros, a legendary brigand chief who once fought for Greek independence. As ransom demands mount and supposed rescuers prove corrupt, the captives discover that survival depends on navigating a treacherous world where heroism and villainy blur, and even escape may not bring the expected rewards. (This is an automatically generated summary.)
These books are free to read. Each is in the public domain in the United States; check your own country's rules before you copy or share one.