Betsy-Tacy through Betsy Tacy Go Over the Big Hill

So here's what you need to know from the first four books : Betsy and Tacy live next door to each other and are the best of friends. Tib comes along several years later and joins them. They live in an idyllic town in Minnesota called Deep Valley. There are some minor characters here and there that you will see in the later books, but when discuss it when we get there.