In 2014’s The Fourteenth Goldfish, by Jennifer L Holm, an aging scientist turns himself into a teenager who must re-enter middle school alongside his granddaughter while they plot to get him back into his lab to finish his brilliant work. A humorous science-fiction novel for middle-grade readers, The Fourteenth Goldfish is the first in a two-book series.   

New York Times Bestselling author Holm has written nearly 60 books for young readers, including the May Amelia, Stink Files, and Babymouse series. She has won three Newbery Honors; The Fourteenth Goldfish won the 2015 E.B. White Read Aloud Award.

A 2016 ebook version contains links to further reading resources; the ebook also forms the basis for this study guide.

Plot Summary

Ellie Cruz lives in a small house near San Francisco with her mom, Lissa, a high school drama teacher. Days after Ellie enters middle school, Lissa returns home from the police station, where she got Ellie’s grandfather out of custody. Standing outside the house is a well-dressed boy in his early teens who complains about the condition of the front yard. He sounds a lot like her grandfather, Melvin Sagarsky, PhD, a researcher.

He is Melvin, age 76. He discovered a rare type of jellyfish that can reverse its own aging, injected himself with a chemical from the jellyfish, and reverted to physical adolescence. He’s just as cranky and opinionated as ever, but now, when he tries to enter his science lab, he gets detained as a juvenile delinquent. Also, he has acne.

Lissa pretends to the police that Melvin is a long-lost cousin. Now in charge of him, she sends him back to middle school with Ellie. There, Melvin complains about the curriculum and teachers, leaves class at will to use the restroom, and gets himself sent to detention.

Melvin teaches Ellie about science and famous scientists—how they never give up until they make great discoveries—and shows her how cooking relies on chemistry. Ellie, who already loves puzzles, begins to see herself as a scientist.

Melvin considers Lissa’s career in theatre to be trivial. He also doesn’t like her boyfriend, Ben, despite his PhD, because he works for a company that makes video games. Melvin complains about how Lissa manages her house and tries to boss her as if she were a teen living with him instead of the other way around. Lissa doesn’t put up with it, though she does complain that Melvin’s teenage appetite is eating her out of house and home.

Ellie misses her best friend, Brianna, who suddenly joins the volleyball team and no longer has time for her. Ellie makes friends with Raj, a low-key guy who dresses in goth clothing. Raj befriends Melvin at school; he doesn’t believe Melvin’s story about a Dr. Sagarsky who claims to have discovered a biochemical fountain of youth, so Melvin proves to him that he’s Dr. Sagarsky.

Melvin’s lab card key gets canceled, and he can’t read his email. Raj joins Ellie as they try to help Melvin break into his old lab and retrieve the jellyfish. They get foiled each time.

Melvin needs papers from his apartment. Lissa drives him there with Ellie, who notes that her grandfather has left everything as it was when her grandmother was still alive. She realizes that Melvin, who thinks people and things aren’t as good as they used to be, wants to be young again partly to revisit his youth.

For a Halloween dance, Ellie wears a mad scientist costume, and Raj shows up as a preppy. They dance together, and Ellie gets lost in the pounding rhythms. She feels a new energy in her life. A few weeks later, she celebrates her birthday at a French restaurant. Melvin says kids these days make too big a deal about birthdays, but he gives her a fancy microscope that she’s delighted with.

Ellie’s father, an actor on tour, visits. The toilet keeps acting up, so he fixes it. He cooks dinner, and they all eat outside. Melvin, who never did like his son-in-law, sulks and goes inside, where he drinks too much wine and throws up repeatedly in the toilet.

Melvin learns that his old lab is being sold, and time is running out to retrieve his jellyfish. Ellie reasons Raj can walk right in if he pretends to be a pizza delivery guy. They buy some pizzas and go to the lab; Raj gets inside, retrieves the cooler with the jellyfish, and escapes.

At school, Brianna approaches Ellie. She didn’t make the volleyball team. Ellie is no longer sad about Brianna; she has Raj and Melvin instead. Brianna thinks Melvin is cute and wants to know if he might go out with her; Ellie says he’s not interested in dating.

The de Young Museum has a mummy exhibit, and Ellie and Raj go. The mummy, an attempt at eternal life, makes her feel uneasy. She tells Melvin that his youth serum, like mummification, is a way of preventing people from living a normal lifespan. Melvin, irate, stops talking to her.

At the opening of Lissa’s high-school production of Our Town, Ellie is struck by a scene in which Emily, who dies in childbirth, returns for a day and laments that people don’t appreciate their life. Ellie looks over at Melvin: He’s engrossed.

Melvin decides that Ellie is right and that he’s been off-course about many things. He flushes the jellyfish down the toilet and leaves to do some traveling. Lissa marries Ben, and they look for a new home with more space for everyone. Ellie receives a package for Melvin that contains a new type of jellyfish that’s even stranger than the last one.