When Ellie's mother shows up at home one night with an opinionated and curmudgeonly thirteen-year-old boy in tow, there is something familiar about him. Imagine Ellie's surprise when she learns that boy is Melvin, her grandfather, who has discovered the cure for aging (thanks to a particular species of jellyfish). The cure comes with some catches: despite actually being seventy-six and having two PhDs, Melvin must attend middle school and live with Ellie and her mother (his daughter, with whom he has a contentious relationship). Ellie, who is growing apart from her best friend, is surprised by her newfound interest in science, thanks to Melvin, and her new friendship with Raj, a goth classmate who is let in on Melvin's secret. Ellie begins to question whether her grandfather's discovery is actually a good thing, wondering what the long-term consequences will be.As Ellie navigates all that comes with being twelve, she ruminates on life, change, beginnings, and endings. Holm strikes the perfect balance of looking at weighty topics while keeping the tone light. The mix of introspection and action (Ellie, Raj, and Melvin need to break into Melvin's lab) keeps the plot moving along. As Ellie learns more about scientists and their experiments, she draws parallels to her own life, thinking, "I'm a jellyfish glowing in the dark sea, bright and brilliant, just waiting to be discovered." This is a smart, funny, and touching story about a family learning from one another and about themselves.Amanda MacGregor.

Gr 5-7 Eleven-year-old Ellie Cruz's life changes dramatically when her mother brings a teenage boy home one night and she learns it is her estranged grandfather. Melvin is a scientist who has figured out how to reverse aging and is now 13 again. Tensions are high between Melvin and his adult daughter, Ellie's mother, but Ellie feels like she now has the opportunity to really get to know her grandfather. Her interest in science blossoms, and she is eager to help Melvin retrieve the jellyfish specimen he used in his experiments so he can publish his discovery. Fascinated, Ellie learns about the work of Jonas Salk, Robert Oppenheimer, and Marie Curie. But as she learns more, she realizes that scientific discoveries often have unforeseen consequences. Readers are carried along with Ellie as she navigates old and new friendships in her first year in middle school with the added complication of her teenage grandfather at the same school. Short chapters keep the story moving at an engaging pace, and the interactions among the characters will easily hold readers' interest. Ellie's growing relationship with her grandfather helps her make discoveries about herself. Melvin, who begins as unapologetically single-minded in his determination to continue his work, also learns from Ellie. With humor and heart, Holm has crafted a story about life, family, and finding one's passion that will appeal to readers willing to imagine the possible. Amanda Raklovits, Champaign Public Library, IL

Middle school doesn-t start smoothly for 11-year-old Ellie, whose best friend finds her passion (volleyball) and new teammates to eat lunch with, while Ellie flounders, uninterested in sports or her parents- avocation, theater. A startling addition to the household helps Ellie get her groove back when Grandpa Melvin, a scientist, moves in

Starred Review It's a little strange for 11-year-old Ellie when her mother brings home a boy who looks to be about 13 but dresses like Ellie's grandfather. But it's a shocker when Ellie realizes that the kid is her grandfather, a scientist who has suddenly succeeded in reversing the aging process. Now sleeping in their den and newly enrolled in Ellie's middle school, Grandpa connives with her to sneak into his old lab and swipe what he needs to continue his research. Meanwhile, Ellie comes to admire the grandfather she has barely known, listens to his stories of famous scientists, and discovers her own passion for science. Written in a clean, crisp style, with lively dialogue and wit, this highly accessible novel will find a ready audience. The idea of an adult in a young teen's body may not be new, but Ellie's first-person narrative makes good use of the situation's comic potential, particularly in the fractious, role-reversed relationship between Mom and Grandpa. Along with the comedy, the story has a reflective side, too, as Ellie thinks through issues such as death and immortality and confronts Grandpa with the social consequences of his research. A great choice for book groups and class discussions as well as individual reading. HIGH-DEMAND BACKSTORY: A three-time Newbery Honor winning author, whose books have also ranked on the New York Times best-seller lists, Holm has a formidably sized fan base waiting for her next release.

Ellie's science-obsessed grandfather finds a way to physically be thirteen again, and his grumpy seventy-six-year-old personality and the limitations of early adolescence make for a comical combination. With its richly entertaining premise, this novel is a breezy read, but it also manages to show off the potential of science and raise big questions about age and ethics.