I love this book. It was written by Mark Twain's grandniece. It's really amazing.
It's about a young orphan who is put through college by a rich "older" gentleman. All he asks in return is one letter a month outlining her progress.
She is told by the supervisor of the orphanage she lives in that the man a) is rich, b) hates girls and c) is to be referred to only as Mr. John Smith.
As she writes her first letter she says she can't call him Mr. Smith, it has no personality. Mr. Rich Man is insulting to him, and Mr. Girl-Hater well same reason. As he left the supervisors office she saw his shadow on the wall it reminded her of a Daddy-Long-Legs spider. So that's what she calls him.
It's a wonderful story. From beginning to end. The sequel Dear Enemy isn't any where near as good. But then again I read it immediately after DDL, so it could just have been that the style was getting dull. If you don't like books written as letters you won't like these. I happen to enjoy that approach.
Obviously I'm not going to tell you how it ends. That would ruin it but I will say, it's a very sweet ending.