The as-yet unnamed heroine finds herself attracted to a large building, a boys' boarding school, which she finds to be strangely familiar. After a little detective work, the disembodied spirit concludes that she is Sally Melford, one of a quartet of eccentric sisters (Imogen, Cart, Fenella and Sally) who live at the school and are neglected by their overworked parents, both of whom teach at the school. Their father, only known as Himself, is the headmaster, and his wife, Phyllis, is the school nurse. Both of them are constantly busy with school business, and leave their daughters to fend for themselves.