Request #427 From Randi

I don’t remember too much about this book, but I will be so amazed if someone helps me find it! I read it when I was in 3rd grade and it was probably a middle age YA book. It featured a group of kids who talk to a Medium! I think they live in an apartment complex. I remember there being some sort of scene where either the group of kids or one of them has to escape the apartment complex by going out on a ledge??  I remember this book inspiring me to answer the popular question “what do you want to be when you grow up?” With: A MEDIUM. I’m sorry I don’t remember more, but I appreciate any help!