Unlike Claudia and Dawn, Stacey's never been much for mysteries and ghost stories. But when she and Charlotte Johanssen hear terrible noises coming out of the old Hennessey place, Stacey thinks the BSC definitely has a mystery on its hands. Mallory claims the house once made her have a horrible nightmare. And Kristy discovers that it was built on top of a graveyard! Does Stoneybrook have a real, live haunted house? The Baby-sitters are going to find out--no matter how scary it might be!