In the mid-1950s, when the Pakistani prime minister Mohammad Ali Bogra falls in love with his secretary, it occurs to him that according to the Islamic principles on which his country is governed, he would be legally within his rights should he take a second (or even a third and fourth) wife. What he doesn’t calculate, however, are the social consequences of bigamy. His decision to remarry so infuriates his first wife, Hamida Bogra, that she initiates a women’s rights campaign calling for reforms in marriage law.

Hamida Bogra’s agitation results in the passage of the Muslim Family Law Ordinance of 1961. Though the statute secures nominal marital protections for women, it fails to ban polygamy or allow women to initiate divorce. So 25 years later, when the writer Rafia Zakaria’s Uncle Sohail falls in love with an officemate in Karachi, there is nothing to stop him from following in the footsteps of the former prime minister. Privately devastated and publicly humiliated, his first wife, Amina, moves back into her father’s home in defeat. Zakaria, then only 10, is perplexed: “I had never known that a man could have two wives.”

Bowing to the pressure of community elders, Aunt Amina eventually returns to her husband’s home, where she lives on the top floor while the second wife occupies the ground floor. “The arrangement when one man had to be shared by two women was methodical, inspired by the Quranic prescription that asked every man taking more than one woman to do so only if he could do ‘perfect justice’ between them,” Zakaria explains. Aunt Amina and her rival agree to spend alternate weeks with their husband. The household is an “oddity”; no other man on the lane has two wives. In their neighbors’ homes, “‘Is Sohail upstairs or downstairs tonight?’ always managed to draw a laugh from the most harried of housewives, the most overworked of husbands,” Zakaria writes.

“The Upstairs Wife” unfolds incrementally: Every new scene in Amina and Sohail’s marriage is paired with a scene from Pakistani history. There is often a wry elegance to these pairings. The original marriage proposal to Aunt Amina from Uncle Sohail comes within days of Pakistan’s forfeiture of East Pakistan (Bangladesh), what Zakaria calls “the first and only public surrender in modern military history”; the year that a distraught Aunt Amina returns to her father’s house, Benazir Bhutto returns to her father’s home, too, after seven years of self-imposed exile from Pakistan. Zakaria juxtaposes private dreams and divisions against public ones to powerful effect. Aunt Amina may be the only woman on the lane who has to share her husband, but she is hardly the only woman struggling to accept the “perfect justice” accorded her under Pakistani law.

The main drawback to this narrative technique is the fragmentation it creates. Zakaria’s historic interludes aren’t consistently chronological and don’t always neatly parallel events in her story; while many of the incidents she highlights from Pakistan’s past function as sharp illustrations of systemic discrimination against women, not all do. Others briefly draw attention to the assorted forces that shaped the country between 1947 and 2007, the year Benazir Bhutto was assassinated: waves of migration, sectarian conflict, a series of military coups, political violence, Cold War tensions, wars with India, wars in Afghanistan, the 9/11 attacks and so on. There’s no single through-line here. Zakaria’s selection of historical episodes raises several books’ worth of unaddressed questions.

Also left unaddressed is Zakaria’s personal story. In the family home, “the windows of the upstairs bedroom from which Amina first saw Sohail became mine,” she writes, and it’s evident from the sensory details she lavishes on the story that her aunt’s fate was, from an early age, a subject of deep personal concern. But how, specifically, might it have shaped her own adult outlook and choices? In the epilogue, Zakaria refers in passing to rebelling from an arranged marriage of her own. “My story was built on hers,” she says of the beloved aunt whose window she inherited. Zakaria, who is a columnist for the Pakistani newspaper Dawn, Al Jazeera America and others, and is a member of Amnesty International USA’s board of directors, has clearly forged a path very different from her aunt’s. But what is her own story, and the story of a generation of Pakistani women like her — the little girls who grew up at the feet of Aunt Aminas everywhere? That, too, might be a question for another book.

These omissions are worth mentioning only because “The Upstairs Wife” does manage to cover so much ground so skillfully, casting a sharp eye on complicated personal politics and affairs of state alike. In the end, Zakaria discovers how deeply entangled her family’s fate is with that of her country. Together they are “knotted and inextricable, inside and outside, male and female, no longer separate.”