Miriam bat Isaac, a budding alchemist and amateur sleuth in first-century CE Alexandria, is concerned when she learns that the threads of gold in the Great Synagogue's Torah mantle have been damaged. She takes the mantle to Judah, a renowned jeweler and the unrequited love of her life. He repairs the threads and assures her that the stones in the mantle are still genuine. Like Miriam, he is astonished that someone would damage the threads but leave the gems behind.

Shortly before, the Jewish community of Alexandria welcomed their visiting sage and his family, who had just arrived from Ephesus on the Thalia. Also on the ship were the perpetrators of an audacious jewelry heist. And shortly after, the captain of the Thalia is found dead in a sleazy waterfront inn.

Can Miriam discover the connections among the jewel heist, the death of the sea captain, and the desecration of the Torah mantle before the deadliest fever claims its victim? Not without help from the bite of a rabid bat.