On the eve of her twenty-fifth birthday, Catherine has spent years caring for her brilliant but mentally unstable father, Robert, a once-renowned mathematician. Following his death, she struggles with grief, uncertainty about her own future, and the lingering fear that she may have inherited his illness. When one of Robert's former students discovers a groundbreaking mathematical proof among his papers, questions arise about its true author, forcing Catherine to confront issues of trust, identity, love, and the fine line between genius and madness.