Gaius Julius Caesar, now Dictator of Rome, has decided to revise the Roman calendar, which has become out of sync with the seasons. As if this weren’t already an unpopular move, Caesar has brought in astronomers and astrologers from abroad, including Egyptians, Greeks, Indians and Persians. Decius is appointed to oversee this project, which he knows rankles the Roman public: “To be told by a pack of Chaldeans and Egyptians how to conduct their duties towards the gods was intolerable.” Not long after the new calendar project begins, two of the foreigners are murdered. Decius begins his investigations and, as the body count increases, it seems that an Indian fortuneteller popular with patrician Roman ladies is also involved.