A strange psychological novel, more in the vein of her Night Over Fitches' Pond than her other books. The plot is motivated by dual personality, not as a phenomenon of nature, but as a deliberate experiment on the part of a doctor, who dies of heart failure as the result of the success of his interference, before he can readjust the lives he has tampered with. And the result -- no one can be sure of the identity of the patient -- and the story is unravelling of the mystery. Plots within plots -- and even the end is implicit of further developments. Fascinating in the telling, and grand reading.