Whitney has a way with old houses, old money, and tough-minded, occasionally foggy old ladies; and in this latest mystery/suspense set in plush Palm Beach, Florida, there are also all the satisfying particulars about chic clothes and great meals to loll about with in between plot twists. Shy, timid Sharon Hollis, daughter of a famous international chanteuse and her glamorous manager, quite naturally agrees to marry paternally protective Ross Logan, a Croesus of oil and banking, when Sharon's parents are killed in a Belfast bombing. Off go Sharon and Ross to his favorite hideaway--Poinciana, an enormous pile brilliantly and creatively designed by Ross' mother Allegra, whom Sharon supposes is dead. Depressing surprises await Sharon: Ross' daughter Gretchen, married, against Daddy's wishes, to European fortune-hunter Vasily Karl, is openly hostile; Jarrett Nichols, Ross' business aide, is puzzlingly cool; the charming Allegra is very much alive, but Ross has banished her to a cottage on the grounds because she supposedly tried to shoot him; and, worst of all, Ross wants to make love to Sharon with her singing mother's portrait on the wall and one of her records playing! There are other revelations: Jarrett's wife died under mysterious circumstances; Ross' second, divorced wife, Brett, is living on the grounds but is not, as Sharon supposed, Gretchen's mother; and there are a number of thefts of tiny Japanese objets d'art. Then Ross dies of a heart attack brought on by shock, and Gretchen will be thrown from a tower. Throughout, there are the requisite creeps and races through secret passages, tumbles down the stairs, conversations half-heard--and everyone is under suspicion, except, of course, the murderer. Less ingenious than some of Whitney's many others, perhaps, but it's still. . . svelte.