In 1468, on the final night of Carnival in Rome, Pope Paul II sat enthroned above the boisterous crowd, when a scuffle caught his eye. His guards had intercepted a mysterious stranger trying urgently to convey a warning--conspirators were lying in wait to slay the pontiff. Twenty humanist intellectuals were quickly arrested, tortured on the rack, and imprisoned in separate cells in the damp dungeon of Castel Sant'Angelo.

Anthony D'Elia offers a compelling, surprising story that reveals a Renaissance world that witnessed the rebirth of interest in the classics, a thriving homoerotic...