The NeverEnding Story (1984)

Bastian is a young boy who lives a dreary life being tormented by school bullies. On one such occasion he escapes into a book shop where the old proprieter reveals an ancient story-book to him, which he is warned can be dangerous.

Shortly after, he "borrows" the book and begins to read it in the school attic where he is drawn into the mythical land of Fantasia, which desperately needs a hero to save it from destruction.