Libby, 12, has Turner syndrome, which makes nonverbal learning difficult and causes some health problems. She struggles to make friends, but her parents are supportive and loving, and her older, marred sister Nonny is her trusted confidante. When pregnant Nonny moves home while her husband is away for a job, Libby is thrilled. She can't wait to be an aunt. But what if the baby has Turner syndrome, too? At school, Libby's wonderful history teacher, Ms. Trepky, assigns a research project on someone not in their textbook. Ms. Trepky also tells Libby about a Smithsonian competition in which contestants must complete an education project about an underappreciated woman in STEM. Libby chooses astronomer Cecilia Payne for the assignment and the contest. She not only admires Cecilia, she often has imagined conversations with her. Libby's contest plan is to lobby for Cecilia's inclusion in the next edition of her textbook. She also makes a deal with Cecilia in her head: If she succeeds, Cecilia will keep Nonny's unborn baby healthy. As she embarks on the project, Libby also makes her first good friend in Samoan American Talia, a new student who shares Libby's frustration with a class bully. Libbys' worries, her determination, her disappointments when determination isn't enough, and her magical thinking around Cecilia Payne and Nonny's baby are all appealing elements of this story featuring an extremely likable protagonist and well-drawn secondary characters. Author Allen, like her protagonist, has Turner syndrome. (Ages 9-12)