Did you know there is a mathematical curve called the Witch of Agnesi? The curve’s name inspired both the title and the protagonist of this novel.
Inspired by scientists & mathematicians from various eras, this novel weaves mathematics, magic, & history into a medieval fantasy setting; i.e., Pythagoras is the "Father of Magic" in this world.

Agnesi Maria Caetana is a prodigy who has possessed immense magical talent & energy since childhood. However, she has a peculiar flaw: she sleepwalks, & during her sleepwalking, she performs feats that would normally be impossible for anyone else—such as using magic to shatter a locked door.
Who will discover Agnesi’s flaw? How can she overcome her weakness?

And that isn't the only challenge Agnesi faces; she must also contend with the Quietus Cloud. This cloud has blanketed the entire surface of the earth, trapping the world in eternal twilight. If Agnesi fails to dispel the Quietus Cloud, what terrible consequences might ensue?