The majority of Charlotte Armstrong’s suspense works detail the perilous voyage of an innocent person who, often by chance, is drawn into an underground world of intrigue and terror. Her stories revolve around whether something will be found or found out before a time limit is reached. Interest is centered on whether something will be done in time rather than on how a problem will be solved. In an innovative manner, she generally traces the progress of both the heroes and the villains as they work to obtain the same goal. Thematically, her fiction brings up a debate between a hard-boiled postwar cynicism and a sentimental idealism; it chronicles the mental distress of a major character who has to forge his own philosophy based on a synthesis of these two attitudes. Her prose also represents a synthesis of these strands, and though generally terse and tense, it is relieved with touches of humor.
Armstrong blends elements from Cornell Woolrich, in the way she reveals a violent underside to the everyday world, and Shirley Jackson, in the way she carefully constructs a dark atmosphere and in her expert character portraiture. Her strong female characters prefigure the independent female characters who were to emerge more fully later in the century, and her frequent use of occult themes anticipated the penchant for the supernatural in popular fiction that was to emerge in the 1970’s.