Nathalie and David are the adult brother and sister mentioned in the title of the book. They are have a very strong bond, although they are not related by blood. They are both adopted. Nathalie decides that she needs to find her biological mother. She insists that David also search for his birth mother. Their adoptive mother and their spouses are threatened by their searches, but this does not deter them. Nathalie and David are both surprised by the identity and personalities of the birth mothers they find. Their discoveries lead them to a greater appreciation of their adoptive mother and their spouses, and to a realization that their lives must change.
This report prepared by Susanna Marlowe