Genteel, bullying Beth O'Donnell, on another uninvited visit to her brother and sister-in-law, leaves their party for their guest cottage and promptly gets killed--causing scarcely a ripple on the Mellingham, Massachusetts, social surface. (``It was a lovely night,'' grieving Merrilee O'Donnell recalls. ``Well, except for Beth, of course.'') The general indifference is due in part to Beth's ruthlessly manipulative habits--she's wheedled an income out of her rich, inoffensive brother Howard, virtually ruined old family friend Lee Handel, and threatened novice editor Bob Chamber with the loss of his job--and in part to first- novelist Oleksiw's disinclination to bring any life to this pallid crew's possible motives for murder. Only a brief appearance by a grinning stockbroker shines with malice. Endless talk about where which well-bred suspect was standing at what moment during the crucial party. For those who care.