Beast and the Halloween Horror (Vintage Paperback) by Patricia Reilly Giff

Halloween should be fun, but Beast is in big  trouble. He was working really hard on his spelling  homework when Ms. Rooney read The Halloween Horror  to the class. Then she told the students to write  to the author.

"Say anything,"  Matthew suggests, and Beast does. He tells the  author he loved the dog in the book. And he even  invites the author to come to school's Halloween  parade, never dreaming he might accept. Then Beast finds  out therewas no dog in the  book.

And now, to make Beast's Halloween really  horrible, guess who's coming to the Polk Street Halloween  parade? And guess who's been assigned to be his  helper?