Rinehart's major themes in K., the first of her novels to be based largely on autobiographical material and to depart from the mystery formula that had served her so well in earlier books, are those of individual freedom and identity. Its protagonist, Sidney Page, is a young woman bound by the social mores of "the Street," where she lives with her widowed mother who runs a boarding house.

Sidney is about to enter training as a nurse, in keeping with the traditional expectations for a woman, but secretly she wants to escape; she longs for the freedom to do something, to do anything beyond what society expects of her. These desires to move beyond the expected social role are symbolized by her androgynous first name. She does not want her actions and achievements to be limited by her gender.

Concurrent with Sidney's struggle against the limitations...