Jeffrey Lionel Magee, who is affectionately referred to as Maniac Magee, is a legend throughout the racially divided town of Two Mills, Pennsylvania. Maniac Magee is a wandering orphan who is notorious for completing nearly impossible feats which leave a lasting legacy and make him a legend throughout the town. Maniac's first amazing feat is running two hundred miles in fifty-one weeks to arrive at Two Mills. He then interrupts a football game and makes an amazing one-handed catch.

Maniac Magee proceeds to enter the horrifying Finsterwald's backyard to save a helpless boy named Arnold Jones. Everyone was scared of the Finsterwald's backyard except for Maniac, who bravely jumped over the fence and rescued Arnold. Maniac also hits a legendary frogball home run off John McNab during a baseball game. Maniac also earns the status of a legend for untying the massive Cobble's Knot, which is an impressive feat that earns him free pizza for life. Maniac is also one of the few white people to cross the racial dividing line of Hector Street and resides with a friendly black family named the Beales. On the East Side, Maniac races and defeats Mars Bars while running backward. Maniac’s feats are memorable and still talked about throughout the town of Two Mills, which makes him a legendary individual.

Jerry Spinelli's Maniac Magee tells the story of Jeffrey Lionel "Maniac" Magee, an orphan.

The story begins with Maniac's parents dying in a trolley accident, which forces him to move in with his aunt and uncle. His aunt and uncle fight often, and this causes Maniac to run away from home.

After running away, Maniac finds himself in the town of Two Mills. While trying to simply survive, Maniac completes many feats that turn him into a legend. Some of these feats include catching a football one-handed, untangling Cobble's Knot, running on railroad ties, hitting a pitch from John McNab, going into Finsterwald's yard, and most importantly, crossing over from the West to East Ends and vice versa.

Many of the feats that Maniac completes are related to sports such as football, baseball, and running, while others are related to social issues. The people of Two Mills are astonished at the things that Jeffrey does and give him the nickname of Maniac. They help him become a legend in the town.

Depending on the source, the definition for "legend" varies in small amounts. In general, most of the definitions focus on a legend being an account of some kind about a historical event or person that is treated as historical but is unauthenticated. The opening chapters of the book do an effective job of presenting Maniac Magee to readers in a legendary format. He catches a long football pass one handed while carrying a book, he hits home run after home run from John McNab's pitches, he survives being in Finsterwald's yard, and he runs on the railroad lines. All of these amazing feats are witnessed by people, but there is no photographic or video evidence of any of it. The feats are so incredibly unbelievable, and there simply isn't a way to confirm the eyewitness accounts, so the out of town kid is quickly named a legendary Maniac.

Maniac is a legend because of all the amazing, crazy things he does. Kids are in awe of him because he is entertaining, talented and brave. Maniac hit the world's first frogball at the end of Chapter 7, a feat which makes him famous among all the kids. He also unties cobble's knot (in chapter 20), which no kid has ever done before. Maniac is often referred to as the "famous Maniac Magee" (such as in the beginning of chapter 35) and everyone knows of him and his fearlessness. There is no doubt that Maniac is a legend!