Books in Sweet Valley Twins Super Chiller series

Playing detective... When a charm school opens in Sweet Valley, Jessica Wakefield can't wait to attend. What could be better than taking classes to learn about clothes, makeup, and going parties? Jessica's twin sister, Elizabeth, has no interest in the school at all--until she uncovers some suspicious things about its owners. Elizabeth convinces her friends Amy and Maria to sign up for classes and do some detective work. But the girls soon realize that charm school isn't as easy as they thought it would be. What's more, Amy and Maria are worried that Elizabeth's sleuthing may put them in real danger. It looks as if the girls may be in over their heads--in class and in their investigation!