Threshold of Fire — Hella S. Haasse

It is 414 A.D. and the once-powerful Roman Empire is in its death throes -- split between East and West, menaced by barbarian hordes almost literally at its gates. The Emperor Honorious cowers in the marsh-bound city of Ravenna, where he has moved the government. There is the Prefect Hadrian, a powerful official and fanatical Christian convert; Marcus Anicius, the pagan aristocrat who is clinging to a dyping past, and the Jew Eliezar ben Elijah, hemmed in by his own traditions and burdened by his dark vision of the future.