One of my all time favorite scary books to share with my students is Wait 'Till Helen Comes written by Mary Downing Hahn and published in 1986. Students who like this book go on to read my entire collection of Hahn books.
Twelve year old Molly along with her brother Michael, her mom, her step-dad, and her bratty little step-sister, Heather, move to the country to a house that used to be a church. The old church comes complete with a graveyard. Heather makes friends with a ghost from the graveyard and warns them that Helen is coming for them.
Molly is worried about Heather and tries to protect her, but Heather twists everything that Molly does, so that she is constantly in trouble with her mother and step-dad.
The back cover says, "It seems as if things can't get any worse, but they do - when Helen comes."
Hahn is good at suspense, and this book with a Lexile of 750 entices the reader to keep turning pages. The print is a bit larger than normal in this slim book with its chilling cover, so even your most reluctant reader will continue to the last page. I can't tell you how many of my students said after reading this book, "Do you have another book like this?"