1348. As the Black Plague lays waste to Italy, Ginevra di Gasparo is summoned back to Florence after nearly a decade of lonely exile.

Ginevra has a gift?using the ancient practices of alchemy she learned as a young girl, she can heal the sick. But when word traveled of her unusual craft, she was condemned as a witch and banished. Now, the same men who expelled Ginevra are begging for her return.

She obliges, assuming the city's leaders are finally ready to accept her unorthodox cures amidst a pandemic. But upon arrival, she is tasked with a much different mission: she must use her collection of jewels to track down a ruthless thief who is ransacking Florence's churches for priceless relics, leaving mysterious vials of brightly colored liquids in their place. If she succeeds, she'll be a recognized physician, never accused of witchcraft again.

But as her investigation progresses, Ginevra discovers she's merely a pawn in a much larger scheme than the one she's been hired to solve. And the dangerous men behind this conspiracy won't think twice about killing a stone witch to get what they want.