When David Norton; an Experimental Psychologist, saves one of his pupils from drowning it is the beginning of a brief but passionate affair. Two years later, Mary Costelloe writes to him out of the blue from Ireland. Married in the interim, her husband has now died and she has inherited Malpas - a vast, crumbling house in Munster. Detecting real need beneath the casual words, he agrees to visit - only to find he has stumbled into a bizarre family case history: a dark story of madness and suicide that stretches back a hundred years. A story that now threatens to claim Mary as its final victim...