It's a rather uncomplicated story. A young girl is out walking in the woods with her mother and her brother. They are squabbling as usual after their parents' divorce and she gets tired of it all.
She falls back behind to be able to avoid listening. After a while she leaves the path to pee. When she comes out again, she can't find the others.
She starts walking in the direction she thinks they went, but of course takes a wrong turn and heads into the heart of the forest, away from populated areas. Now and then she listens to her Walkman to keep her mood up. Sometimes she listens to the news to find out where they are searching for her, sometimes she tries to find a baseball game, perhaps even with her favorite player Tom Gordon.
While she starts to take steps to survive by conserving what little food she had with her, picking berries and so on, her mother and brother return to their car without her and call the police and start a search. Naturally, they search in the area around the path, but not as far away as she has gone.
As the cops stop searching for the night, she huddles up underneath a tree to rest. As she stays out longer, she starts to see things that she rationally shouldn't be able too see. After a while, she starts seeing Tom Gordon and talking to him.