Eleven-year-old Ellie’s scientist grandfather has discovered a jellyfish with anti-aging properties. Ellie learns this the day her mom comes home with a young teenage boy who seems vaguely familiar. It’s her grandfather, Melvin. Ellie has never been particularly close to her grandfather, who’s always been critical of her theater-teacher mom, but now the two of them are peers. Melvin doesn’t change a thing about himself to attend middle school, still dressing like a seventy-something-year-old man except for his long hair (“If you’d been bald for years, would you cut it?”). Unable to get back into his lab because no one recognizes him, he enlists Ellie and their new friend, Raj, to try to help him get to his research. Meanwhile, he’s opening Ellie’s eyes and mind to the fascinating world of science — of things we cannot see that are happening all around us, of things that are waiting to be discovered, and of problems waiting to be solved. She’s captivated, but as Ellie delves deeper into the world of science, into the life-changing and sometimes shattering work of scientists like Jonas Salk and his polio vaccine and J. Robert Oppenheimer and the Manhattan Project, she realizes there is more than just the wonder of discovery and the challenge of problem-solving. There are also questions about ethics and moral responsibility, some of them hitting close to home. Jennifer Holm’s story is funny and engaging and effortlessly thought-provoking. (Ages 9–12)