Four For A Boy (John, the Lord Chamberlain Mysteries, 4)

Nominee, Bruce Alexander History Mystery Award
Best Little Known Series, Booklist
It's unnaturally cold in Constantinople this winter of 525. The Emperor Justin is dying, and Theodora, the ambitious former actress his gravely ill successor Justinian intends to marry, is making demands in the imperial court.
When a wealthy philanthropist is killed in broad daylight in the Great Church, it isn't entirely surprising that Justinian engages an anonymous young slave called John to investigate what many believe could be a conspiracy aimed at swaying the succession. Suspects are many among those whose lives might be touched by an emperor: senators, churchmen, wealthy businessmen, even laborers, beggars, and prostitutes.
In this prequel to the series, John takes his first dangerous steps along the path toward freedom from slavery and his eventual appointment as Lord Chamberlain.