Nic Stone’s young adult novels tackle some of the most difficult subject matters imaginable. Her bestselling 2017 novel, Dear Martin, tells the story of a young Black man coming to grips with the work and philosophy of Martin Luther King Jr., while experiencing police brutality in today’s America. The sequel, her latest book, Dear Justyce, was inspired by two of Stone’s teenage mentees, who asked her to write a book that represented them. Stone’s writing succeeds because of her strength of heart: One of the things that makes her books (and our conversation) so memorable is her remarkable generosity of spirit. She describes herself as an “eternal optimist,” but Stone also has a keen understanding of human nature and of history. Black, queer and a mother herself, she is...