A murder, a suspicion, an intrigue on the trail of a conspiracy in Roman Trier. On his way home from the governor's palace, a high official is murdered. Suspicion falls on his slave Hyacinthus and thus, according to Roman law, all slaves of the household are threatened with execution. The young slave Invita carries out her own investigations. She uncovers a conspiracy that endangers not only her own life but the entire city of Treveris.