Back cover text:Jessica Wakefield is convinced that Mary Wallace has disappeared. No one has heard a word from her in three days. She hasn't been in school she didn't show up for Lil's ice cream party, and worst of all, the Unicorns' treasury money seems to be missing. What's more, Mrs. Wallace, Mary's mom, is acting very strange.Jessica's twin sister, Elizabeth, thinks that Jessica is just being her usual overdramatic self, until the twins get a mysterious and confusing phone message. Maybe Jessica's idea isn't so farfetched after all. Maybe Mary has been kidnapped. If that's the case, Mary is in big trouble... and the twins had better figure out that cryptic phone message fast.