Mary Anne should never have thrown away that chain letter she got in the mail. Ever since she did, bad things have been happening to everyone in The Baby-sitters Club. With Halloween coming up, Mary Anne's even more worried — what kind of spooky thing will happen next? Then Mary Anne finds a new note in her mailbox: Wear this bad-luck charm, it says. OR ELSE. Mary Anne has to follow the note's instructions. But who sent the charm? And why did they send it to Mary Anne?