Our narrator introduces himself by telling us he was once nicknamed "kicker." See, when he was little, he would kick all the other kids in daycare. Not the most promising introduction. But it turns out "kicker" is really just a big softy. He outgrows the kicking phase, and now everyone just calls him Max.
Here's what you need to know about Max: he's huge and he lives with his grandparents. By the time he is in 8th grade, he is the size of a grown man. His size and a few other details make him sort of an outcast, but he soon befriends fellow outcast Kevin, who Max lovingly calls "Freak." Freak is tiny (foil alert?) and insanely smart.
These two boys could not be more different, but they quickly become close friends. That's right: opposites attract. Freak tries to teach Max about robotics and history, and Max just sort of smiles and nods like he understands. Freak also tells Max that he is going to become the first human/robot hybrid. (A) That's awesome. (B) That means Freak is going to have an operation that will make him stronger so he won't be sick anymore. But it's a really big secret, so Max can't tell anyone.
After hanging out for a while, this dynamic duo forms "Freak the Mighty," which is basically Freak sitting on Max's shoulders. Together, these two are unstoppable; after all, it is Freak's huge brain on Max's huge body.
The boys go on a bunch of adventures and quests together, one of which involves returning a woman's stolen purse. Seems like a nice thing to do, but it all goes horribly wrong. It turns out that the woman, Loretta Lee, isn't so much a damsel in distress as a woman who causes distress. And don't get us started on her boyfriend Iggy, who knows Max's dad.
Oh, and did we mention that Max's dad is currently in prison for killing Max's mom? Yikes. This horribly violent act has earned him the nickname Killer Kane. When Max and Freak finally get away from the adventure-gone-wrong, Max doesn't want to talk about his dad. All Max wants is to forget it ever happened.
Not so fast. Killer Kane ends up being paroled, and he kidnaps Max on Christmas Eve. Luckily, Freak works with the cops to find Max and rescue him. After he's safe and sound, things settle down a bit, and Max even starts doing better in school.
But don't get too excited.
When summer comes around, it's time for Freak's birthday. He gets a computer from his mom with some fancy newfangled invention called a modem that lets him dial up to the school computer. (Yep, this is what the Internet used to sound like.) What's with all the new technology? It's so Freak can go to school from home. Hmmm. Max doesn't understand why Freak wouldn't be able to go to school; and when he asks, everyone gets really quiet. Before Max can get any answers, Freak has a seizure and is rushed to the hospital.
At the hospital, Freak gives Max a blank book and tells him to fill it with their adventures. He explains that he is getting his new robotic body and he won't have time to write their adventures; he'll be too busy learning how to walk with long legs. Max agrees, but he's hesitant. After all, he's not the smart one—Freak is.
The next day, Max goes to visit the hospital, but learns that Freak died during the night. Max goes nuts, kicking people and punching glass windows. Finally, after he is subdued by security, Freak's doctor explains that there never was a secret operation. Freak made it up to have something to hope for.
Max spends the next year alone and majorly depressed. Then one day, he takes out the blank book Freak gave him, and he starts writing. He writes for a long time. And when he's finished, he has written a book called Freak the Mighty.