Minor tempests in a terribly genteel teapot--as Graves (retired editorial director of Time-Life) follows the rich Winderman clan through one summer at their multi-house vacation compound on a fashionable island off the New England coast. The family patriarch is loving yet imperious ""Ah-boo"": retired professor Charles Winderman, a widower about to celebrate his 70th birthday. His middle-aging children are banker Lawrence, ad-man Brad, and boozy divorcee Martha--all of whom appear every August with their kids. But the primary viewpoint here is that of an outsider/newcomer: Lawrence's second wife Ellen, 32, a very pregnant ex-career woman with some reservations about Winderman family life. Ellen's two college-age stepsons have remained distant, occasionally hostile. (On the other hand, she has warm rapport with stepdaughter Nancy.) More important, Ellen bridles a bit at Ah-boo's lordly insistence on his many patriarchal prerogatives and the traditional family-rules. And she becomes actively rebellious when Ah-boo forbids Nancy to bring her new boyfriend to his 70th-birthday bash: the boyfriend, von see, is Anthony Balto, son of a prominent native Islander (""the purest, most successful proponent of 'Get it from the summer people' ""). First, Ellen tries all sorts of persuasion on gently, firmly snobbish Ah-boo. When all these efforts fail, she gets angry--though she refuses even to consider the blackmail possibilities. (Christopher, Ah-boo's moodiest grandchild and a compulsive snoop, offers Ellen some ammunition about Ah-boo's secret sex-life with housekeeper Bonjy.) But finally, to husband Lawrence's horror, Ellen gets her way by threatening to boycott Ah-boo's party herself: the patriarch is, in fact, moved to tears--feeling that strong, sensitive Ellen (who has also won over her stepsons) has what it takes to succeed him as actual (if not official) family chieftain. In outline, then, this close-up of WASP-family traditions in transition may remind you of The Late George Apley or A.R. Gurney's play The Dining Room. Unfortunately, however, Graves lacks the style and wit of those precursors (or of Louis Auchincloss at his best), the Winderman family-rituals (picnics, tennis, etc.) are blandly, over-indulgently detailed; the characterizations remain superficial. And, despite a flicker of zest in a few of the subplots, this is pleasant short-story material at best, puffed out into a stodgy, humorless, inoffensive summer-porch snoozer.