"I Am Forbidden," a Novel by Anouk Markovits Anouk Markovits was raised a Hasidic Jew in France, but at 19 she fled her community to avoid an arranged marriage. She went on to get a master's degree in architecture and a Ph.D. in romance studies. "I Am Forbidden," her first novel in English, centers on two Hasidic sisters: one who leaves, and one who stays, shunning modernity. Given the author's background, you might assume that this is a story about how one of them is wrecked by her choice. But the wonder of this elegant, enthralling novel is the beauty Ms. Markovits unearths in the Hasidic community she takes us into. She remains largely nonjudgmental about the most difficult-to-grasp practices of the Satmar sect, while showing how even the most fervent believers struggle with the letter-of-the-law faith. The involved plot, sweeping across four generations, opens in Transylvania, along the Hungarian-Romanian border, just before World War II. A 5-year-old boy named Josef plays with his little sister, Pearela. He's just crawled under a table after her and whacked his head when he hears heavy boots clomp into the house. He sees his sister stabbed with a pitchfork. He hears his mother's screams in the yard, and then it is quiet. Ms. Markovits reports this chillingly: "Pearela's dress grew darker. It was night, then it was day. A gold curl escaped the crusted, maroon sheath that now encased Pearela. The gentile maid, Florina, finds Josef and takes him home, disguising him by cutting off his sidelocks. Five years later he watches a family of Jews be shot as its members run for an open box car leaving town. A little girl survives; her name is Mila. He places his hand over her mouth, tells her not to speak "the Jew language" and gets her to Rabbi Zalman Stern, who takes her in. There she shares a bed with Zalman's daughter, the 4-year-old Atara, holding her hand night after night before the shock lifts and she can speak again. As they grow up, the girls" closeness remains a refuge. Atara's mother, Hannah, is busy having babies, while Zalman is joyless and angry. When the children come in one day, flushed from playing in the Luxembourg Gardens (the family moves to Paris to escape the sweep of Communism), he reprimands them: "Why so much joy in the wilderness?"The orphan Mila never chafes against the tight binding of the ancient law enforced by her new father. Zalman reminds her of the strong incentive to obey: "When you observe HaShem's commandments, your parents" souls, up there, come nearer to His presence, but when you stray, they are banished to a cold desert where souls freeze and shatter." Message received. It is Atara who begins to wonder about life on the outside; soon she's smuggling nonreligious books under her covers. She wants a secular education, but such a thing is forbidden. When she feels she can no longer speak freely to Mila, she turns to inanimate objects. To the polished stones, Atara confided that one day, courage might call for a bigger self, not for making oneself smaller. At 16, she packs a toothbrush and some underwear and steps into the Parisian morning and out of her family. It will be 47 years before she and Mila speak again. Underscoring the idea that she was "the one who left, May Her Name Be Erased,"as her family puts it, Atara vanishes for much of the second half of the book. Instead Ms. Markovits, big-hearted and surprising, tenderly captures the complexities of adulthood for the one who stayed: Mila, who ends up in the Satmar community in Williamsburg, Brooklyn, in an arranged marriage with the very Josef who saved her. On their wedding night, the two separate as soon as Mila bleeds, because she is considered unclean - this moment too is prescribed by the law - and yet the closeness between them is not lost: "At dawn, he was still sitting by her bed," Ms. Markovits writes. Later, "her eyes flicked open, so big in her unadorned face, and he uttered the first prayer of the day, "Modeh ani ... shehechezarta bi nishmati ..." I thank Thee ... for returning my soul within me .... When, after years, Mila has not produced a child, her despair is acute. "There was not much to be, in Williamsburg, for a woman who was not pregnant," Ms. Markovits writes. Despite their love for each other, after 10 years an Orthodox Jewish man could no longer abstain from the commandment to "be fruitful and multiply." And so it is that the force that brought them together, their shared devotion to their faith, now threatens to undo them. As plot-heavy as it sounds, "I Am Forbidden" whips by, its extravagant narrative steadily cast with complicated, thoughtful characters. When Atara reappears, five decades later, she's a filmmaker living in a loft in Lower Manhattan, evidently alone. We know that over the years she's longed to hear from Mila. Is she happy? Ms. Markovits leaves that question unanswered.