Sunjeev Sahota's "China Room" is an intelligent, earnest novel, and although one of its story lines is weaker than the other, it's consistently absorbing, a sweeping dual portrait of a woman forced into an adolescent marriage and the troubled descendant she'll never meet.

The book's main thread — set in 1929, in an India increasingly resistant to British rule — focuses on an unwillingly engaged 15-year-old. Mehar's impoverished parents have agreed that she'll marry the son of a domineering, relatively wealthy widow named Mai. Adding insult to matrimony, Mehar hasn't met her husband-to-be. The wedding day won't provide any clarity.

Her future mother-in-law has arranged for Mehar and two women — Gurleen and Harbans — to wed her three sons in a single ceremony. Mai's interpretation of the family's Sikh faith requires that the brides be "shrouded from head to foot in … gown[s] and gold drapes." The men wear "curtain[s] of white marigolds," obscuring their faces. Eager to set a dictatorial tone, Mai won't tell the brides who's marrying whom.

In the weeks after the ceremony, Mai sows confusion by ordering the young wives to spend most of their hours in the family's cramped "china room," so "named for the old willow-pattern plates" on the shelves. But gutsy Mehar won't "remain dutiful, veiled and silent." She persuades her sisters-in-law to play hopscotch. She comically impersonates Mai.

Mehar eventually finds love, but not with her husband, Jeet. She and Suraj, Gurleen's husband, appear to be soul mates. With brutal colonial rule threatening to plunge family and country into chaos — the English are extorting Indian landowners, and "Free India" militias are enlisting soldiers — the lovers hatch a dramatic escape plan.

The Mehar plot is intertwined with a slighter tale. Seventy years later, her great-grandson flees his home in England and isolates himself in Mehar's now-abandoned house. Eighteen-year-old S—, as he's known, is trying to kick a destructive heroin habit when he falls for an older woman. Radhika is a busy doctor working amid devastating poverty, yet she somewhat implausibly spends countless hours doting on the relatively spoiled teen.

S— recounts the violent bigotry threatening his family back in Britain, but aside from this distressing subplot, his story line isn't terribly robust. Fortunately, Mehar gets more ink.

Sahota, a Booker Prize finalist in 2015, is a talented prose stylist. His description of the "champagne brightness" of daybreak in India — "The morning mist was dove-grey and light and lifting away from the fields" — is among many gorgeously crafted passages. He relates Mehar's story in moving detail, and while the S— saga is comparatively underwhelming, his linking of the plot lines is never jarring. It's a flawed novel but often a powerful one.

Kevin Canfield is a writer in New York City.

China Room
By: Sunjeev Sahota.
Publisher: Viking, 256 pages, $27.