Katya Geller learned from her mother that math was the answer to everything. Now, approaching forty, she finds this wisdom tested: she has lost the love of her life and has just found out that her mother is dying. Katya turns to the unfinished notes for her mother's last textbook, hoping to find guidance in mathematical concepts. Katya traces back her life's journey: her childhood in Soviet Russia, her parents' great love, the death of her father, her mother's career as a renowned mathematician, and their immigration to the United States. She is haunted by a question: how to parse the wild, unfathomable passion she feels through the cool logic of mathematics?