A young doctor named Ethelbert Croft recruits the help of the great psychologist Dr. Yznaga in diagnosing and treating the problems of Viscountess Torbeth. She suffers from what would now be called multiple personality, although Vincent Harper calls it “complex personality.” At intervals, she undergoes a complete change of identity, releasing a second self far less inhibited than the primary one.
The patient’s father, Dean Chelmsford, immediately opposes Yznaga, disapproving strongly of his materialistic theories. Yznaga insists that there is no such entity as the soul or “ego” (in the religious sense) and that personality is merely the product of the electrical and chemical activity of the brain. The clergyman cannot accept this and begins a campaign of defamation against both Yznaga and Croft. Yznaga fights back against this vilification, delivering strident speeches in which he looks forward to the defeat of all superstition and the establishment of a more rational society by virtue of psychological technology.
In order to test Yznaga’s method of personality manip-ulation, Croft submits to an experiment. His own identity is suppressed, and the false identity of Edward Templeton is superimposed on it. In a further phase, the dor-mant identity is obliterated, so that Templeton becomes the sole inhabitant of Croft’s body. Yznaga and his colleagues are completely satisfied, but Templeton—having no knowledge of the experiment of which he is a part— takes leave of them before they can set matters right.
Templeton goes to Dresden, Germany, where he falls in love with a woman named Gertrude Leighton. He is arrested and charged with fraud on the evidence of Dean Chelmsford, who identifies him as an impostor. The situation is further complicated by the fact that Gertrude Leighton is Lady Torbeth’s alter ego. Yznaga arrives in time to rescue Templeton and restore the identity of Ethelbert Croft to its rightful station, but the problem of Lady Torbeth—whose amorous version Croft earlier met under the pseudonym of Muriel Errington—remains for a little longer. In the end, Yznaga is allowed to apply his treatment to the viscountess, successfully annihilating the less conventional—and hence less convenient—element of her dual personality.