Plain Jane Singer, the star of this irreverent--and irresistible--first novel, is a wry, romantic, Jewish truth-teller. With her finely tuned, built-in radar for phonies, she's an updated, female Holden Caulfield from Cleveland. Jane, the valedictorian of her high-school class, has sidestepped college for a secretarial job in a psychiatrist's office. She wants to remain close to Dr. Stevens, her onetime shrink and heartthrob. Also, it seems important to be at home, keeping an eye on things these days when her once close-knit family appears to be unraveling dramatically. It all started with Jane's older sister Caroline getting married to Jonathan Klausner, a doctor from an Orthodox family in New York. Already, Caroline has become more Klausner than Singer, disdaining her own family's customs, following her new mother-in-law's heavy recipes, saying ``Pesach'' instead of ``Passover,'' pretending to be virginal after her promiscuous Cleveland days. After this initial family defection, others follow in the form of death and imminent divorce. Jane stitches as fast as she can in a hopeless effort to patch her family back together. Meanwhile, she's feeling the weight of a couple of guilty secrets she's carrying around: She's engaged to a man she doesn't love, and, worst of all, she's sure she's responsible for the trauma that has affected her younger brother, Willy, making him a kind of pathological fibber. Oy. Just how much responsibility can one smart, sassy, 19-year-old mensch be expected to take? Luckily, Jane figures out the answer. And by novel's end, she's well on her indomitable way to figuring out the rest of her life. When she does, watch out. A plum of a first novel--ripe, juicy, and not exactly strictly kosher.