Wait Till Helen Comes. A Ghost Story

Twelve-year-old Molly and her ten-year-old brother, Michael, have never liked their seven-year-old stepsister, Heather. Ever since their parents got married, she's made Molly and Michael's life miserable. Now their parents have moved them all to the country to live in a house that used to be a church, with a cemetery in the backyard. If that's not bad enough, Heather starts talking to a ghost named Helen and warning Molly and Michael that Helen is coming for them.
Molly feels certain Heather is in some kind of danger, but every time she tries to help, Heather twists things around to get her into trouble. It seems as if things can't get any worse. But they do-when Helen comes. A Legendary Middle Grade Horror Story: From master of spooky suspense Mary Downing Hahn, this is the chilling ghost story that has been terrifying readers for generations. Stepsister Rivalry: Molly and Michael's new life in a converted church is hard enough, but their seven-year-old stepsister, Heather, seems determined to make them miserable.
A Haunted Graveyard: When Heather discovers the lonely grave of a girl named Helen in the backyard cemetery, she claims to have made a new friend. But Helen is not a nice friend. Chilling Suspense: Molly must unravel the truth about the ghost haunting her family before Helen's promise to come for them becomes a terrifying reality.