Cary Grant has done a relatively splendid job of keeping his private self private--as made clear by the wall-to-wall blandness of this routine celeb biography. True, Godfrey has gotten a few quotes from relatives about Grant's earliest years as Archie Leach in Bristol, England: his mother's disappearances (into a mental institution) when he was nine; his father's near-poverty; his first exposure, as an electrician's assistant, to theater (""The adolescent Archie Leach had met his apocalyptic moment""); his leaving school at 14 (it ""remains a matter of mystery, inviting speculation""); his joining-up with the comic-acrobat troupe that brought him to New York. But once Archie Leach moves from Broadway musicals to (as Cary Grant) Hollywood movies, Godfrey's information is almost entirely second-hand, with no fresh testimony worth recording. Thus, this is largely a movie-by-movie plod--from the star-making rums with Mae West to Grant's emergence as a light comedian in Sylvia Scarlett (""Grant's almost apocalyptic moment""); from superstardom beginning in the late Thirties to his wisely choosy later years and his 1966 retirement: ""At the summit, his luster undimmed, a great star walked away without a backward glance."" There are also perfunctory notes on his brief first two marriages; his longer one with Betsy Drake, who introduced him to hypnosis and the ""confidence and serenity"" of controlled LSD usage; fatherhood, and ugly divorce, with Dyan Cannon (""So much bitterness . . . And yet so much happiness""); and post-retirement life as a heavy-dating businessman. As for the affair with Sophia Loren, Godfrey merely paraphrases her own memoir. And the assessment of Grant's glorious yet limited career is pallid, not even comparable to Pauline Kael's recent essay. Mostly leaden (all those ""apocalyptic"" moments), occasionally flip--and duller than anything starring Cary Grant has a right to be.