Betsy, Tacy, and Tib are now old enough to do a lot of things...including going bobsledding and venturing into town on their own. They discover the joys of the public library, riding in a horseless carriage, and the theater. And as if it weren't enough to see a real play, they find themselves acting in one. They find a new friend, Mrs. Poppy, whose husband is the manager of the theater. Although Mrs. Poppy lives in a beautiful house with red carpets, gold chairs, and lace curtains, Betsy discovers that she is lonely just the same. But the three girls are going to make sure that changes.