Showing Beast in View by Margaret Millar

At thirty, Helen Clarvoe is alone: her only visitors are the staff at the hotel where she lives, and her only phone calls come from a stranger. Until that stranger, with a quiet, compelling voice, lures the aloof and financially secure Miss Clarvoe into a world of extortion, pornography, vengeance, madness and murder. But who is the hunter and who is the victim...? A gothic chiller which still feels incredibly modern, BEAST IN VIEW is a true classic of the crime fiction genre.