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 (c) Copyright 2014. Library Journals LLC, a wholly owned subsidiary of Media Source, Inc. No redistribution permitted.