The ghost's are Alice who has been in the house the longest and Sandra. Alice was a wife and mother who was abused, Sandra was a drunk. They each lived in the house during different era's in time.
In the time of the book, the house was owned by the recently deceased Richard Walker. His estranged family come to the house in order to claim their inheritance and to deal with Richard's final arrangements. His ex-wife Caroline is a bitter drunk, Trenton his son, is a suicidal teenager who was in a horrible accident, Minna is Richards daughter who is really pretty messed up with the way she thinks and feels towards pretty much everything, and then little Amy, Minna's daughter.
I have to say this was kind of a peculiar (maybe) story. It was not scary even though there were ghosts. But it was a book that you just had to keep reading. Just to see where it all ended.