13-year-old Kevin "Freak" Dillon suffers from
Morquio syndrome and lives with his mother Gwen "Fair Gwen" Dillon. Due to his disability, he walks with leg braces and crutches. Meanwhile, 15-year-old Maxwell "Max" Kane has learning challenges and lives with his maternal grandparents Susan "Gram" and Elton "Grim" Pinneman. He has flunked the seventh grade twice and is tormented by teenage delinquent Tony "Blade" Fowler, who leads the "Doghouse Boys", a bully gang. Kevin is assigned as Max's reading tutor. Kevin and Max go to a festival to watch a firework show and get attacked by Blade's gang. The two escape into a lake with Kevin riding on Max's shoulders. Max subsequently starts carrying Kevin around on his shoulders during their adventures. During a visit to a museum, Kevin uses
Sir Galahad's sword to knight them as "Freak the Mighty." Kevin witnesses Blade's gang putting someone's purse in a sewer. The two retrieve the purse but are confronted by the gang. They attempt to attack Kevin, but Max stops them by picking up a
manhole cover and throwing it at the gang, who flee in panic. The purse belongs to a woman named Loretta Lee, so Max and Kevin return it to her. Loretta is married to former gang leader Iggy. The couple are old friends of Max's father Kenny "Killer" Kane, who is in prison for the murder of Max's mother. On Christmas Eve, Kenny kidnaps Max after being released on parole and takes him to Iggy and Loretta's apartment. Loretta tries to help Max escape, but Kenny catches her and attempts to strangle her. Max's seeing the attack prompts a repressed memory of Kenny murdering his mother; he breaks free of his bonds, rants about the memory, and attacks Kenny. After tracking Max and Kenny, Kevin breaks in, armed with a squirt gun that he lies is loaded with
sulfuric acid. He sprays it in Kenny's eyes. Before an angered Kenny regains himself and attempts to hurt Kevin, Max tackles him through the wall where the police are waiting; Kenny is then returned to prison for life without the possibility of parole while Kevin and Max run home to have Christmas dinner with Gwen, Grim, and Gram. While exchanging Christmas gifts, Kevin gives Max a blank book and tells him to write in it. That night, Kevin dies in his sleep due to heart problems. The following weeks, Max continues attending school but spends his spare time locked in the basement, missing Kevin's funeral and seeing Gwen moving away. He later runs into Loretta at a bus stop, who says that "doing nothing's a drag, kid". He takes this advice to heart and decides to write all the adventures he had with Kevin in the blank book. Max gets writer's block on the last page and puts an illustration of
King Arthur's grave which reads "Here Lies King Arthur, Once and Future King". Max then takes Kevin's ornithopter and winds it up, making it fly. ==Cast==