A 268-page letter from Jack, a Gainesville, Ga., violinist whose orchestra is out on strike, to his older brother and former manager Lenny--who has just gotten a White House staff appointment. Between reports on the tense, funny strike negotiations (including some contempt-of-court time in jail), Jack reminisces about their shared-room Brooklyn-Jewish adolescence in the late Forties, attempting to figure out, once and for all, the truth of their relationship. ""You think we've grown apart. I think we were never close. We both think we love each other. So let's see what's doing."" What's doing is the familiar Big Brother/ Kid Brother hero-worship and rivalry, but Brody balances the soupy generalizations (""We were really learning loneliness"") with the muted crackle of a hundred affecting, convincing specifics: Jack's bar-mitzvah, when Lenny persuades him to play Bach instead of making the customary speech; the quiet testing of prospective wives at family dinners; a nightmare evening out (Mary Martin in South Pacific) as one of Lenny's marriages collapses; Jack's impossible life as a concert soloist, becoming ""famous"" rather than ""great"" under Lenny's shrewd, selfish supervision. And Brody's humor, unlike that in so many hoistings from the urban-Jewish well, is gentle and unforced. (""Jack? I think maybe we don't have to thrash so much"" whispers wife-to-be Molly as they effortfully lose their virginities.) True, the monster-letter format grows more and more ungainly, and the brink of bathos is always just a schlep away. But Jack and Lenny and company are drawn, albeit with more sincerity than skill, from unexaggerated, share-able lives--so the awkwardnesses here are almost as touching as the many moments of smooth accomplishment.