Something's not right at number 56 Water Street. From the sidewalkin front of the abandoned house, ten-year-old best friendsDerek and Ravine watch lights flicker on and off, again and again.When they race home to tell their parents, they're in for a shock:there is no house at 56 Water Street!The house is invisible to everyone but Derek and Ravine, and theghost haunting the old place wants to get their attention. Trappedfor more than a hundred years, Isabel Roberts needs to solve themystery of her younger sister's fate before she can truly rest inpeace. And she's chosen Derek and Ravine to help her.When the two friends summon the courage to venture inside thehouse, they're unprepared for what they find (after all, meeting aghost face-to-face isn't exactly normal) and for the spine-tinglingadventures in store for them. But Derek and Ravine are determinedto help Isabel. If they don't, she could be a ghost forever!