R.M. Ballantyne 
Pirate City [EPUB ebook] 
A Tale of the Pirates of the City of Algiers, and Their Defeat by the British Navy

What starts out as a pleasant family sea voyage takes a nightmarish turn in R.M. Ballantyne’s The Pirate City. A prosperous Italian businessman and his sons are captured by a crew of pirates and are forcibly entered into servitude in the vast, roiling den of iniquity known as "Pirate City." They make the best of their horrific ordeal, but will they ever be able to escape and make it back home?