Maniac Magee's parents died in a trolley accident when he was three. Without a home, he moves in with his aunt and uncle who dislike each other to the point of not communicating. While living with them, Maniac runs away during a school musical never to return.
After a year, he mysteriously shows up in Two Mills. The town is racially divided with white people living in the West End of town and black people living in the East End of town.
While walking in the East End on his first day in town, Maniac meets a girl named Amanda Beale carrying a suitcase. Mistaking her for a runaway, Maniac approaches Amanda and discovers she is carrying her prized collection of used books.
Later, as Maniac is walking around the East End neighborhood, he meets Mars Bar Thompson, the neighborhood’s bully. Mars questions why Maniac is in the neighborhood and steals Amanda’s book.
In the middle of the scene, Amanda shows up and scolds Mars while demanding he return the book. She brings Maniac into her home where he is introduced to the Beale family. Amanda’s family consists of her mother, father, and unruly brother and sister.
After it is discovered Maniac is homeless, Amanda’s family welcomes the orphan into their home. Maniac loves his new family but soon discovers the neighborhood isn’t as welcoming as the Beatles are.