Window on the Square — Phyllis A. Whitney

THE SCENE IS NEW YORK CITY IN THE 1870's. A letter summons young Megan Kincaid to the house on Washington Square. In a startling interview the master of the house, Brandon Reid, informs her that he wishes her to devote herself to moody, unbalanced Jeremy, Mrs. Reid's son by her previous husband, Brandon's younger brother Dwight. Dwight Reid's brilliant career as New York District Attorney had been ended by a shocking and tragic accident with a gun--or so the newspapers had claimed--at the hands of this same guilt-ridden child, then aged seven. Against her better judgment, Megan accepts the challenge.
From the beginning Megan feels uneasy in the house; she senses the presence of lurking evil, of mysterious emotional undercurrents, of relationships that are not what they appear to be. She does not know whom to trust--the haughty yet strangely sad beauty, Leslie Reid, or the somber, fascinating master of the house, whose warm voice belies his cold, grave manner. She finds herself irresistibly drawn toward him, and their growing mutual attraction is duly noted by interested members of the household. When Megan realizes fully the extent of her own feelings, she knows she cannot honorably remain in the Reid home. Yet she also knows that if she goes, Jeremy will be left alone in world, irretrievably lost.