Susannah bat Jonah is Jonathan ben Mordecai's mother.
Susannah remained behind in Jerusalem when her husband, Mordecai, and her children, Miriam and Jonathan, left, leading them to believe she had been killed. In actual fact she stayed to be with her first love, Jonathan the Zealot. Later, Susannah also claims that her father, a Jewish priest, disapproved of her husband's conversion to Christianity and his "cowardice" in refusing to fight the Romans. Her parents and Jonathan died in the siege and she was enslaved, becoming a handmaiden to Berenice in the Golden House. After Berenice's departure, she befriends Titus, who shows interest in her faith and her opinions. She becomes known as Susannah the Beautiful.
In The Assassins of Rome, she is found by Jonathan, who is shocked, but overjoyed to have been reunited. Susannah tells him she has thought of him every day since they parted, but that she cannot come back with him as Titus needs her. She does not have an unpleasant life in the Golden House, where she is well fed and looked after. She is a skilled seamstress and is at her loom most hours of the day. Her decision to stay angers Jonathan, as he interprets this as her telling him that she loves Titus more than her family.
In The Enemies of Jupiter she returns to live with her family. However, she has a separate room from Mordecai. She appears to be restless and spends a lot of time wandering around Ostia, with her hair uncovered, which causes the local people to view her as slightly odd.
When the four detectives are exiled in The Man from Pomegranate Street and go and live in their villa in Ephesus, Susannah decides to stay behind in Ostia, firstly for Soto and secondly so that she is there if Mordecai returns, as he had gone missing. However, it pains her immensely to see her son go and she tears her hair and weeps as he departs.
- The name 'Susannah' is of Hebrew origin and means 'lily'.