I read this book OVER and OVER as a kid. I was fascinated by the way it dealt with time and with fate. A family of kids go to live in an old house. In the course of exploring, they meet ghosts of kids who once lived there and learn how to travel through time in order to help those kids. Just typing this, I again had chills running down my spine and goosebumps. Oddly, I had my own ghost story connected with this. I can't share the details, since it involves a past client who had died, but suffice it to say that an interaction after I re-read this as an adult in my 30s brought me closer than I have ever otherwise come to believing in an afterlife. VERY freaky.