I have been a huge fan of Milton since Nathaniels Nutmeg, which was a phenomenal story. The whole point of his books are to take periods of history, little understood, and create a vivid story. It would be wrong to say it reads like fiction, because one is fully aware you are reading a book of history, but it is told with so much enthusiasm and poise as to make it eminently readable.
The story, as one would guess, is of the little known tale of white slaves that were captured bu the Barbary corsairs and sold to such places as Morocco and Algiers (Algeria). It goes into graphic detail about the conditions and brutality they endured, and the cruelty of their owners, particularly a despotic sultan of Morocco. I mean, you couldn't make up moulay Ismail, a brutal and ruthless villain, who was so unpredictable he could sometimes forgive even treason.
The character we follow is a chap called Thomas Pellow, captured at 11, and subjected to 23 years (ish) slavery. It follows his beatings, his enforced conversion to Islam, his rise in authority in the grandiose palace of Meknes, to when he even defied the Sultan yet lived. He then became a renegade, and thought in an army of such people, and made numerous desperate escape attempts.
Utterley absorbing. We follow sieges, naval battles, tortures, awful executions, daring emissaries, desperate escapes, betrayals. You couldn't ask for much more. If you like your history fast paced and bloody, this is for you.