As the book opens, we are introduced to our main characters, and it's clear that these two need each other. Together, they form Freak the Mighty.
Freak the Mighty go on a bunch of adventures and seem to overcome every obstacle in their path. Freak explains that he's going to undergo a secret operation that will give him a bionic body. This explains why he has to go to the hospital so much—or does it?
Max finally has to confront the memory of his mother's death, and Freak has to overcome his physical limitations. Both of these come to a head when Killer Kane kidnaps Max and Freak rescues him.
On his birthday, Freak has a seizure and is rushed to the hospital. He asks Max to write down their adventures, and that night, he dies in the hospital.
How does Max find closure from Freak's death? After he spends a long time mourning his friend, he picks up the blank book Freak left him and begins to write their story. Could this be the beginning of something new for Max?