The cover illustration depicts a brain with strange, purple liquid being poured onto it.
Two aliens, Morggul and Gobbul, have landed in Maplewood, New Jersey looking for strong and smart humans to serve as slaves on their planet. They are hiding in the house of Dr. Frank King, as they think he is king of the scientists. But he is not as smart or as strong as they want.
Frank's nephews, Step-siblings, Nathan and Lindy Nichols come to visit him. They tell him that they are mocked for being the stupidest kids in school. They study constantly but always get low marks, and were unable to build a dollhouse for their younger sister Brenda. They believe Frank can help them become smarter. He gives them a concoction called "Brain Juice', which is actually just grape juice. He believes that if they think they are smarter, it will boost their confidence. Morggul and Gobbul see this and replace the grape juice with Brain Energizing Fluid, which will make the kids smarter so they can become fitting slaves.
At first it doesn't seemed to have worked, but eventually it kicks into high gear. The teacher even believes they have cheated on a test because of how well they did. They start correcting the teacher in class and start annoying the class by flaunting their newfound intelligence. Even their friends refuse to hang out with them, believe they are freaks. They upset their peers so much that they are expelled for being too unnaturally smart.
Following their expulsion from school, Nathan and Lindy are soon hounded by news anchors who are reporting the controversy over the two being kicked out of school, agents who want to make them famous, and government scientists who want them for experiments. After a while, Nathan and Lindy get so terrified at the thought of being famous.
As Nathan and Lindy run away from home, Morggul and Gobbul finally catch up with them and tell them what they did. Nathan and Lindy are abducted and taken to Gobbul and Morggul's home planet to be presented to the emperor, but the effects of the Brain Juice begin to wear off and Nathan and Lindy soon act stupid again. Gobbul and Morggul are disintegrated, while Nathan and Lindy are sent back to Earth.
Back home, it's revealed that Nathan and Lindy were only pretending to be stupid so they won't be slaves to the alien emperor and must keep pretending to be stupid in order to return to their normal lives. They tell Frank what happened, and make him swear to never tell anyone about the aliens. Frank then reveals he has been drinking the same brand of grape juice he gave them, 8 times a day.
- In France, this book is the 63rd book of the original Goosebumps series. Its title was translated into "Concentré de cerveau", which means in English Brain concentrate or Brain extract.
- This is one of the few books in the series to start with a prologue, the first being Creature Teacher.
- The tagline for this book, "A mind is a terrible thing to drink," is a reference to UNCF's slogan, "A Mind Is a Terrible Thing to Waste."
- This slogan had already been referenced by R.L. Stine in the 1995 Fear Street book, Switched.
- This book references Nerf, The New York Times, Jeopardy!, Coke, and Gatorade.
- The name Dr. Frank King is likely a play on Dr. Frankenstein.
- In an interview with Entertainment Weekly, R.L. Stine said that, of all the books he's written, this one was among his favorites, but it was often overlooked.
- The cover artwork displayed on Scholastic's website for this book is slightly different than the actual cover art. Their version uses the tagline, "This is your brain. This is your brain on juice." This tagline is a reference to This Is Your Brain on Drugs, an anti-narcotics campaign led by Partnership for a Drug-Free America.
- The title of this book was teased in late-1996 — prior to the release of Beware, the Snowman. Stine mentioned the title in 1997; however, at the time, he hadn't yet decided on a plot. The book was reportedly finished by March 1998.
- This, Scream School and Slappy's Nightmare are the only Goosebumps Series 2000 books to be written in the third person.
- The concept of kids getting a special ability that the media and government try to take advantage of, and pretending to lose it to go back to having a normal life was previously done in How I Learned to Fly.
- The concept of aliens giving humans a special gift as part of an experiment was likely inspired by the Twilight Zone episode "Mr. Dingle the Strong". That episode involved super strength but it ends with another alien giving him intelligence, just like in this book.
- There was a contest called the "Brain Juice Terrifying Title Contest" made to promote this book, where kids would come up with a scary story title and Stine would come to the winner's school to finish the story. The winning title was "Dead Dog's Still Fetch" by Braden Gardener.
Reference in other Goosebumps media
- This book is referenced in Goosebumps: The Game as an achievement called "Using Good Ol' Brain Juice."
- Read this, not that: 'Goosebumps' author R L Stine on his summer book recommendations (mirror)
- Scholastic: Goosebumps 2000 #12 / Brain Juice / By R. L. Stine (mirror)
- "The Bumps" — "Brain Juice, but that will be something over #60." (archived)
- "The Bumps" — "Ask R.L. Stine!" October 14 (archived)
- "The Bumps" — "Ask R.L. Stine!" March 16 (archived)