The Burning Stakes, A Novel of the Late Roman Empire - The Embers of Empire, #6

To unite the warring Roman army under his fresh command, Emperor Julian offers his military enemies a free hand over a sinister show trial purging the late Constantius II's court. As the names of the generals' targets leak out from the Chalcedon tribunal, panic and betrayal engulfs civil servants, imperial eunuchs, and even the agentes in rebus. Agent Numidianus returns to Rome to discover his headquarters under a new chief and his ailing intelligence master Apodemius gone missing.
With a trusted few, he fights to protect the Magister's most vulnerable secret ever- while defending himself against charges that will tie him to the executioner's stake. Packed with action and intrigue, the Embers of Empire series is delighting fans of Bernard Cornwell, Steven Saylor and Robert Harris.