In 1524, a man named David Reubeni appeared in Venice, claiming to be the ambassador of a powerful Jewish kingdom deep in the heart of Arabia. In this era of fierce rivalry between great powers, voyages of fantastic discovery, and brutal conquest of new lands, people throughout the Mediterranean saw the signs of an impending apocalypse and envisioned a coming war that would end with a decisive Christian or Islamic victory. With his army of hardy desert warriors from lost Israelite tribes, Reubeni pledged to deliver the Jews to the Holy Land by force and restore their pride and autonomy. He would spend a decade shuttling between European rulers in Italy, Portugal, Spain, and France, seeking weaponry in exchange for the support of his hitherto unknown but mighty Jewish kingdom. Many, however, believed him to favor the relatively tolerant Ottomans over the persecutorial Christian regimes. Reubeni was hailed as a messiah by many wealthy Jews and Iberia's oppressed conversos, but his grand ambitions were halted in Regensburg when the Holy Roman Emperor, Charles V, turned him over to the Inquisition and, in 1538, he was likely burned at the stake.

Diary of a Black Jewish Messiah is the first English translation of Reubeni's Hebrew-language diary, detailing his travels and personal travails. Written in a Hebrew drawn from everyday speech, entirely unlike other literary works of the period, Reubeni's diary reveals both the dramatic desperation of Renaissance Jewish communities and the struggles of the diplomat, trickster, and dreamer who wanted to save them.