You can read this and other reviews at Things I Find While Shelving 
 [I received a free ARC of this book via NetGalley. This fact has no bearing on my review.] 
 Ellie's life gets a little strange when a thirteen year old boy comes home with her mom and claims to be her grandfather. All evidence points to him telling the truth, and Ellie is whisked into the world of science and "discovering the possible" as she tries to help her grandfather retrieve the specimen that made his life's work - reversing aging - possible. 
 Ellie learns about Oppenheimer and Curie and Salk and she discovers that she takes after her grandfather rather than her parents when it comes to her passions. She has an affinity for and a love of science that she begins to nurture as she finds her place in middle school - drifting away from old friends, making new ones, and keeping her grandfather out of trouble... 
 But Ellie finds herself facing the question: is her grandfather's discovery a good thing or a bad thing? Is it the kind of scientific discovery that will change the world for the better, or is it something that is better left alone? Ellie isn't sure, and she has to get her grandfather to ask the question as well before he brings his discovery to light, ensuring the world will never be the same. 
 This was a very fun book, and I really enjoyed reading it. I felt like sometimes, within the narration, Ellie didn't feel as young as she's supposed to be. But over all I really liked this and it's super fun and yay for characters being excited about science! 
 3.5 stars.